I used to think it was disgraceful that you had to pay for the beach in Italy, but have been to different parts of Italy and realise they just do “going to the beach” differently. If you just want to have a swim, there are parts you can access free.
But if you want to spend the day, as Italian families do, you can choose one of the fenced off sections, pay a fee, and for that you may get a lot more than just sun lounger and umbrella. There are usually changing cubicles, toilets, showers, bar and restaurant with excellent, reasonably priced food. If going to spend a whole day at the beach, it may be worth paying for the facilities.
Some parts of Italy, like the south coast of Sicily have lots of uncrowded, free beaches, other parts are very popular and may be hard to find a decent bit of beach without paying. As OP says, it’s something to be aware of if planning an Italian holiday that involves beach time.