So if Starbucks and McDonalds accepts crypto in El Salvador, why not in the USA, UK and rest of the world?

The title pretty much sums up my question. What’s holding big companies like Starbucks and McDonalds from accepting crypto in other countries like the USA, UK and rest of the world?

Is this a local government thing? From My understanding anyone in the US can accept any crypto for services/products if they chose to do so.

Or is it that because the government says it’s a legal tender in El Salvador that this companies are forced to accept crypto as payment?

Another thought does the government have to accept each crypto as legal tender to make these companies accept it?