Crypto is a multi billion dollar market, why hasn't a single solution for micropayments managed to achieve commercial uptake? Everyone would benefit if such a solution existed and was cheaper than Visa/MC.

Crypto having low transaction costs at anything resembling commercial scale TPS seems to be a myth. There's always some giant gaping caveat that goes unmentioned, like "lightning network Bitcoin" or "eth 2.0 with PoS will solve this".