Italian radio and television stations, aided by new technology and a court ruling ending a government broadcasting monopoly, are proliferating in a free-for all reminiscent of the heyday of American radio a half-century ago.

While most European countries offer a meager choice of three or four channels, often government-sponsored, Italy now has some 300 independent television channels and more than 2,000 private radio stations. All are local, all carry advertising.

With hundreds of ventures starting up and going under each year in a virtually regulation-free atomsphere, the situation at times approaches chaos as rival companies intrude into competitive frequencies and jam each other's transmissions.

The current trend stems from court rulings a few years ago that abolished the monopoly on broadcasting held by the government's Radiotelevisione Italiana (RAI). The rulings coincided with technological innovations that brought down the price of setting up new stations, and the boom got under way.

At latest count, Rome had 43 television channels, Turin 18, and most other large cities have at least a dozen private stations. Altogether the independents have about a quarter of the total Italian audience, up from about 15 percent two years ago.

The government-subsidized RAI networks surpass the independent stations in quality of news, documentaries and expensive spectaculars. The RAI stations' absence of advertising is refreshing, compared to independent stations, one of which in Palermo devotes more than 30 percent of its prime time to commercials.

For the most part, the local private stations turn out a dreadful diet of vintage Westerns dubbed into Italian and interspersed with commercials for neighborhood real estate agents and automobile dealers.

Some of the stations provide hardcore porn on the late, late show, and one presented a strip-tease by several women claiming to be local housewives. Another station featured a village witch demonstrating the use of herbal cures.

But many small stations render community service by providing down-to-earth advice on taxes, pensions and other problems in contrast to the generally more-highbrow fare on the government channels.

Almost inevitably the wild assortment of local stations will be amalgamated into something like an independent national network. Large advertising, publishing and film interests are already moving in that direction, and politicians are taking sides on the inevitable issue of government regulation of the independents.

Telemilano, a northern Italian corporation plans to form a 10-station network in its area with an original outlay of some $14 million. Similar enterprises are taking shape in other parts of the country, and eventually only about 100 private stations are expected to survive.

As the independents merge they are seeking to improve their programming by hiring famous stars, buying sophisticated equipment, building impressive studios and acquiring up-to-date movies.

Feeling the influence of the independents, the government system is trying to win back the share of the market lost to the independents by allowing more staff autonomy to produce livelier programs.

Italy would not be Italy without politics. The nation's various political parties have rushed to take advantage of the boom in private television.

The ruling Christian Democrats, who have close links with the businessmen who manage the industry, are estimated to have the support of 70 percent of the private stations. The Communist Party, with less chance of such support, has tended to be hostile to the independents.