Or under any realistic payment system that end users would want to use

No offense, but micropayments have to be the most often suggested non-solution to any problem since the "402 Payment required" code was added to the HTTP spec

I think hypothetical/magic micropayments that just work(TM) actually solve lots of problems. The problem is with the “realistic” part, which is why it always comes up.

Idk, I’d pretty happily pay $0.50 to use an infrequently used utility once, if it was totally effortless. But everything wants like $20-30, or even worse, to lock me into some monthly subscription.

That level of effort is something I think matters a lot. If you could make it incredibly easy for people to spend $1-2 (and no more), you could get a TON of money out of people. I dunno how you'd solve that major structural issue, but if you could, it sounds like a goldmine. If nothing else, microtransactions in software would probably explode more than they already have.

Sadly, the only micropayments implementation we have is ad-supported apps. It's essentially micropayments. Albeit a very annoying implementation!