Wow, I've lived in the USA all my life and never heard that people living in the UK had to buy a TV license to watch TV. I visited London (loved visiting!) last year and still never heard about the TV license.
Here in the US we don't have to buy a TV license. In most areas in the US depending on where you live all you need to watch TV is an over the air roof top or set top antenna and a TV. The antennas cost as little as $20 USD. Where I live receive about 20 HD digital channels completely for free. However, only about 6 of those channels broadcast our major network TV such as ABC, CBS and NBC
To receive sport channels (ESPN) or channels like Science or Discovery you have to subscribe to a cable or satellite TV service package which cost anywhere from $50 to $200 / month depending on how many channels you want and there a hundreds of channels to choose from.
With all that said the old school broadcast TV channels are realizing that more and more people in the US aren't watching TV anymore and are just streaming whatever they want to watch on Netflix, Hulu, Disney Plus, etc. IMO if TV companies don't move over their content to streaming services they are really going to go the way of the dodo!
Cheers from across the pond! :)