Goes like the following: Google/YouTube have a userbase to track accounts for; they go to a bank (licensed money transmitter, with OFAC/KYC/AML programs implemented). Google gets paid by people looking to advertise, and that money goes into Google's master account. Google's finance system translates views/impressions to money movements to creator accounts hosted at other banks (same deal, OFAC/KYC/AML program in place). The main thing is, every party that actually moves around money, operates in such a way that the entire transaction chain is followable. It's not point to point, it's hub and spoke. The hubs keep track of everything to keep the Osama Bin Laden's or Russian Oligarch's, or Cuban nationals out of the U.S. financial system.

"Micropayments" have always been something different. We technologists just figured there would be a way we could whip up some accounting software, or a spec, and allow people a way to store and transact without relying on a custodial holder, with all the extra regulation burden. Point is though, government and law enforcement don't want that, because with that, it becomes a great deal more difficult to follow the money, or to get away with things like mandating everyone report money movements over some amount to the tax authority; something easy to do when it's tacked on to the condition of maintaining your license to do business. Every money transmitter being well behaved and integrated with the state maximizes the risk for anyone attempting to utilize the financial system for illegal activity.

Ergo... What you think of as already solved isn't "micropayments". It's traditional finance in the U.S. What we refer to when we say Micropayments, is a way to store value, maintain accounts, and run point to point transactions "blessed" or recognized by the world et al without an intermediary.