A lot of legal problems around it.

Not hard to move the value across the border. In most cases the assets are not moved but rather counted towards offsetting traffic in opposite directions.

But the problem is with local laws and regulations - they easily target the local "entry/exit" points where actual money changing hands.

It becomes too complex and too risky for small local operators.

That's why Western Union and other remittance companies exist and banks still charge exorbitant fees for wire transfers.

As people get fed up with it they move to crypto currencies.

But wide adoption is still a challenge. Also it's relatively hard for an average consumer to get the money in and out of crypto. Even though transferring is easy.

With wider adoption remittance will no longer be needed. Anybody should be able to transfer anything to anyone and it should cost nothing like an email.