Exchanges allow for sub-second resolution of a transaction because the resolution is actually pushing numbers around in the exchange's own internal tables (or between trusted exchanges). Banks offer similar service when trading fiat currency (either because they can resolve an internal account-to-account transaction or because they'll float the risk of fraud until they can resolve a cross-firm transaction). But if you want to have the Bitcoin network agree on a transaction, it has to get buried several blocks deep in the chain, and that takes time.

Ah, yes I don't disagree. IMO, I don't think the use case for crypto is to replace fiat, but I can see how those that operate from that assumption/desire would experience friction.