For years, scholars have been telling Foggy Bottom and Capitol Hill that Latin America exists only as a georgraphic unit, and that a one-poncho policy cannot cover all of the varied sociesies south of Texas.

No one has officially disagreed. Nonetheless, Washington policy-makers have continued to launch a series of Special Relationships, New Realisms and New Dialogues with the assumption that some overall community of goals exist among the Latin countries and between Latin America and the United States.

To some extent, the behavior of Latin Americans has encouraged this assumption.

A high State Department official recently summarized the difference between Latin America and other developing regions this way:

"You might say that African nations tend to see the U.S. in terms of a permanent adversary, sort of like a trade union views a big company. But Latin Americans are like the guy who goes to work in the big company sweeping up at night, willing to work his way up to become chairman of the board some day. They're seeing their future in terms of cooperation with us for mutual profitability," the American official said.

But no Latin Americans are seriously challenging this concept; more so with the advant of President Carter's avowed determination to include respect for human rights in his policy equations.

Increasingly, decision-makers in Latin America are questioning the benefits they thought they were getting from the United States, redefining their own goals, and looking around to see where they can get the best deal. No longer is the United States automatically seen as the best possible market for their raw materials or the best possible source of loans and technology.

Although decades of buying made-in-USA products and relying on U.S. know-how, aid and advice have caused Latin Americans to look north, their devotion to things American is superficial.

For all the transisitor radios belting can rock music, the less-visible institutional underpinnings and attitudes that support the American lifestyle receive less ddication than lip service in the southern half of the hemisphere.

Tothe extent that the basic Western Europen enets of free expression, good citizenship, saving and investment, and public service crossed over to both Americas, they have tailed to propsoer in Latin American, where historical circumstances have differed greatly from those in North America.

The result is that the societies of Latin America and the United States appear no longer to be seeking the same goals.

North Americans are commonly accused of viewing the "typical Latin American" - a breed that does not exist, according to residents of any Latin American country - as the Indians of the high Andean plateaus: dark, uncommunicative, picturesque, probably barefoot and wearing a funny hat.

In fact, if there were a typical Latin American now, it would probably be a married 19-year-old of mixed Spanish and Indian blood who dropped out of school early and now works a six-day week to support two children and a wife in a run-down urban neighborhood.

For contrary to the stereotype, South America has become an urban society, with 61.8 per cent of its people in cities and the urban population growing at 4 per cent a year, according to figures from the Inter-American Development Bank.

People here to go to the cities for the same reasons their forebears came to the continent: opportunity, education, a better life for the kids. Leaving behind vast empty spaces and unexplored wilderness that would be a frontier if anyone saw any future in staying, they crowd into city slums.

jobs are scarce there: Although the continent-wide unemployment rate is officially only 5.8 per cent, according to the U.N. Economic Commission for Latin America, the figure is universally understated for political reasons.

Furthermore, millions of those counted as employed are actually underemployed, selling candy or shoelaces in the streets.

Despite the exploding urban population, some governments encourage large families because huge stretches of territory are underutilized - Bolivia's vast natural eastern pasture, for example, is 90 per cent empty - while people are going hungry.

It all adds up to what the U.N. commission calls "grave poverty" for fully 43 per cent of all Latin Americans, more than 110 million people. Yet it would be wrong to assume that eradicting this poverty is the No. 1 priority of governments in the region.

Explored first by conquerers who came to loot, not to seetle, most Latin American nations suffered through generations of warring rulers and local chiefs whose primary aim was personal enrichment. Later the winners brought in foreign companies to take out the minerals, the oil, the bananas and the rest, building vast social and economic systems around a few primary products.

Governments were bought and sold like pomegranates, while generations adapted to survive and even prosper at the expense of their compatriots. The poor were simply the losers, rules were for those with no pull and critics were for mortal enemies. Only in the last 25 years or so - and only in some countries at that - have social revolutions taken place to combat these conditions.

Economic nationalism has been the main force driving the Latins to revaluate their relations with the developed world, especially the United States.

"It wasn't so much OPEC itself that changed the world as it was the howls of rage from the consumer nations," said a Brazilian banker. "We realized we'd never get decent prices as a gift from you. We finally learned we'd be dependent forever if we didn't do something about it ourselves."

But regional efforts at cooperation have foundered on mutual suspicion and advantage-seeking as each country drives to ex ploit its own natural resources while at the same time becoming self-sufficient and independent of any foreign control.

For all the US preaching about trust and cooperation in development, Latin nations' relations with Washington, with one another and with their own peoples are, in fact, ruled by mistrust.

This is evident in the forests of alleged safeguares bureaucracies throw up around the most minor transactions, to foil a public assumed to be cheating; in the mighty frontier defenses and outsize military establishments, and in the wars against guerrillas, the far left and the press that sputter on throughout the continent and occasionally break into the open.

The picture, then, is that of a region whose governments tend to choose calm over kindness, to put their credit ratings ahead of democratic institutions. They apparently would rather that things not work at all than root out the corruption that greases the wheels.

Working hard just to hold their internal disparities within bearable limits, most Latin governments find it hard to focus on what ever community, of interest they may have with their immediate neighbors. They have ceased to listen to announcements from their giant northern neighbor about how much the two entirecontinents have in common.