>Courts, law enforcement and contract law.

That's the wrong answer. The existence of tokens predates the existence of government. It's the next step after barter. The correct answer is reputation. A vendor who cheats his customers builds up a bad reputation, and the only way he can keep doing it is by changing customer bases, for example by moving to a different town. Think of the traveling snake oil salesman who moves on once people realize his remedies don't work.

A crypto advocate would argue smart contracts can fulfil that role, but also that applies in developed countries but not in the countries where the vast majority of the world population lives.

I think if a true crypto economy does emerge anywhere it's likely to be Nigeria, Lebanon etc - places with a significant population of educated entrepreneurial people but where the state is run abysmally and you can't rely on those institutions anyway

That is not where trust in the dollar comes from.

It comes from stability. Predictability.

Courts and law enforcement certainly provide these things, but they are not required. The inherent design of blockchains makes them trustworthy (an oversimplified statement), which is even better.