Lynn,
Here's a link to the page you need to read, it is available in English too.
It clearly states
" Persons residing abroad but holders of a place of abode in Italy equipped with a television set are also held to pay subscription fees. "
RAI - Radiotelevisione italiana - Abbonamenti
I recall we paid our first one pro rata for a part year and subsequently we have been sent a bill to pay each year. It is due by the 31st of January every year and our bill arrived yesterday - this year's fee is 109 euros.
There is also a possibility to pay in two instalments of 55,63 (Jan & July) or 4 instalments of 28,97 (Jan, April, July and October).
I imagine the folk you have asked just haven't ever bothered buying a licence - but they do have detector vans here just as they do in the UK.
Hope this helps, Lesley