About the cars: It's a good thing that, if you want, V will be able to steal them to use, but not to sell or keep.
First because it would break the economic system, by giving you a way to make easy money.
Second: because there will be a lot of different vehicles to try before deciding to buy.
Third: if the game gives you a lot of free stuff, there is no reason to collect resources.
There is one more thing about "making the cars easy to steal": We don't know if that's true. The game is not realeased, but I really expect that the police will be smarter than in the other games with this mechanic, something similar to RDR 2 (People call the cops, they will chase you for a while, then, as time pass, your "bounty" slowly decreases).
And about crimes having "real consequences". It's very hard to implement a "real life" consequence in game.
a) If it's death, then it's "game over - reload" cycle.
b) If it's prison, depending on how long the player is kept in jail, it's either "reload" option, or "escape" option. Both can become very boring to repeat, so that's why the police system have to be harsh, but not that harsh.
c) If it's a fine that the player have to pay. If he get caught, he will probably pay or reload the game. And depending on the value, the steal mechanic can become obsolete.
d) The only cool thing that I could think of was making the jail as a way to have more side quests, but only for the first or second time (it could have a mission or two in jail, did you do that CDPR developers? Thinking about it now, it would be cool), after that it would be hard to maintain the same interest (the game is Cyberpunk 2077, not Thug'n'punk 2077)
So, making the cars possible to steal but not to sell, is because the developers want the player to try other cars and move fast in the map (not forcing the player to walk), but not turn it in an exploit mechanic, or unrealistic ("Stolen car? cool, I pay 1% of it's price, so you don't exploit that"), that's why, IMO, it's a good decision.