icowden
Squire
Not sure where you get your "large" percentage from. 95% of households (27,000,000) have a TV (or way of watching TV) and TV license evasion is at around 7.25% (1,025,000).A large percentage of the U.K. don’t even pay the fee. Nobody ever bothers to check on them.
Also many people may not have a TV but will still watch bbc on phones & devices without a license.
https://commonslibrary.parliament.uk/research-briefings/cbp-8101/
Checks are carried out - usually by checking the license database against a government postal address database and looking for unlicensed homes - the assumption being that everyone watches TV and will need a license.
On your last point though, I think you are right and it becomes ever harder to enforce TV licensing due to the proliferation in ways you can watch the TV.