Until sharding provides a tunable level of security, we will see this waste of computing power.

Then, that might enable more payments for cheaper, which might let you pay by the minute and such.

But the second main brake in adoption is legal. Many countries' jurisdictions require lots of bureaucracy to earn money from various places of the world. For example, EU has VAT, which requires bureaucracy for EU country-to-country payments even if you are exempt (Register of Intra-Community Operators). This negates pretty much all the advantage of trustless/decentralized businesses (ease of payments).