Many things you can't do, but what they don't know, can't hurt them.
Same as dealer. He buys car and settles it and gets papers in 7 days. Sometimes he already sold it before the papers arrive.
Dealer is very different.
1. Can settle in cash so there is no hassle.
2. Has access to dealer plates and other services a casual person on the street doesn’t.
Dealer knows once it’s paid the papers will arrive and has a separate contract with the buyer that it will happen.
Casual street oke requires buyer to settle it and then provide papers so not really the same thing at all.
There simply isn’t a profit to be made in this picture.