Not entirely sure what is debatable about this situation. You quite unambiguously derived revenue from a UK citizen here, although not much. If you didn’t want that revenue, then don’t display ads in the UK. If that makes serving traffic to the UK uneconomical, then don’t serve traffic to the UK, problem solved.
In practical terms, nobody’s give a crap about you making a couple of dollars here and there incidentally from UK citizens. It quite another matter when your business is clearly dependent on deriving revenue from UK citizens, and you take zero steps to try and comply with UK law.
It’s pretty simple, if you want the revenue, the you have to follow the law of the countries your deriving that revenue from. Don’t want to follow the law, then simply don’t try and derive revenue from putting adverts in front of citizens from that country, or by collecting and selling their data.
You have a level of plausible deniability there.
Most of these jurisdictions can't actually do anything about it, but they can claim they will. The UK might actually be in this situation.