Global transfers are slow because they generally undergo some form of manual review for risk and AML/KYC. Crypto is fast because it pretends that this isn't a requirement. That only works as long as it's small enough people don't care. Once people care, things will look a lot different than they do now.

There's no reason whatsoever that a crypto payment would be faster than a traditional payment - in fact, there's a ton of reasons the lower bound is much slower.

This is an intentional process decision, combined with some (replaceable) outdated technology. However, the former strictly dominates the latter.