In the darkened room, the family of five sat huddled around the large color television set, using a remote-control device to run rapidly through Rome's two dozen channels before deciding on the evening's choice.

The scene and the ample selection of television offerings -- musical variety shows, cultural programs, debates and an infinity of American films and TV serials -- would not be unusual in the United States.

But with about 600 private television stations reportedly now operating here, Italy is the only European country to have effectively done away with the state radio and televison monopoly traditional on this side of the Atlantic.

According to a recent poll, about 22 million Italians -- almost half of the country's TV audience -- watch at least one private station a day. This provides RAI, the state company, with competition it simply is not prepared for.

To all appearances, the proliferation of private television stations has delighted Italian viewers, whose choice until a few years ago was limited to two nationwide, state-controlled networks that went off the air at about 11 p.m.

But it is a situation that has come about not by design but by default. Five years after Italy's constitutional court issued a surprise ruling saying the national monopoly of the airwaves could not apply to local broadcasts, the government has yet to pass a law regulating the use of frequencies, distributing them, issuing licenses and deciding just what broadcasting range a local station may have.

The problem is not one of technical unpreparedness but a lack of political will.

In the case of the Italian airwaves, two laws prepared since 1976 by the Posts and Telecommunications Ministry were allowed to fall by the wayside, ostensibly because of governmental crises. A series of laws provided by individual political parties were never brought before parliament. And the latest draft bill -- already months behind schedule -- is likely to be further delayed because its author, Postal Minister Michele di Giesi, a Social Democrat, was replaced by a Christian Democratic colleague.

In the meantime, the private television channels and thousands of radio stations have simply occupied available frequencies. The result has been a radical change in viewer habits, not to mention a powerful multimillion-dollar TV advertising industry. Both have probably become permanent Italian fixtures.

After a brief flirtation with strip shows and soft-core pornographic films, the private stations have been relying on films and television serials purchased abroad for about 80 percent of the programs they broadcast. The private stations have made a beeline for the United States, leading some Italians to worry that their country risks being "culturally colonized." In 1980, more than 80 different American television programs, old and new, could be seen on Italian television.

Even the state company, RAI, has been making a stab at its competition by purchasing programs like "Dallas," broadcasting an increasing number of films and gradually pushing back its sign-off time. It also added another network to its two previous offerings.

"But," says RAI President Sergio Zavoli, "we are a public service network and cannot sacrifice our identity to total scope entertainment."

Zavoli says the legislative vacuum "has been a problem" and threatens to set off an indiscriminate purchasing race for spectator-grabbing entertainment.

A massive organization with a history of politically motivated, executive-level hirings, RAI has produced well-known and successful films like the Taviani brothers' "Padre Padrone," Ermanno Olmi's "The Tree of Wooden Clogs," as well as high-quality TV epics like Franco Zeffirelli's "Jesus."

But many of its programs are criticized for being paternalistic, didactic and often boring.

The proliferation of private stations has caused technical problems -- interference with air and sea traffic, telecommunications satellites and RAI. It also has led to complaints from neighboring countries where state control of the airwaves is intact.

But above all, the failure to act earlier has permitted the development of a chaotic situation that will be difficult to reverse. What's more, although the constitutional court's decision made it clear that private national networks were not to be permitted, at least four of the new broadcast companies have been quietly building consortiums and accumulating affiliates, giving themselves a more-than potential nationwide audience.

Three of these are offshoots of major Italian publishing houses, Rizzoli, Mondadori and Rusconi. Last December Rizzoli's "Primarete Independente" (PIN) began broadcasting a daily news program in four of Italy's 20 regions. Following a protest by the Postal Ministry and RAI, the case was sent to the constitutional court whose ruling could represent a crucial watershed.

Giorgio Bogi, undersecretary at the Posts and Telecommunications Ministry, said eventually a law will be passed that will somewhat rationalize the situation.

But, he said, prolonged failure to act means that a return to the state monopoly of the past has now become impossible. Inevitably, in his view, Italy will have a "mixed system" in which RAI, controlled by the Italian parliament, and the market-oriented private stations will play distinct cultural and economic roles.