There is a smart contract, it's on Hive-engine.
The artist has to choose which license to attach to his/her art: Private or Full Commercial.
Some artists send their owners the physical art too, but that is up to the individal artists to decide.
For me, I just create digital work, now, but I am considering sending something to the people who buy my art.
If i have a falling out with the artist, it would be illegal for them to mint this piece of art somewhere else. Their reputation would suffer, which would affect their future sales.