If cars are lockpickable they are useless. If it turns out that there will be hundreds of cars all over the place then its a simple matter to increase the cost of running them, to reduce the numbers.
If you want to make enemies, try to change something.
Just make the cars discoverable somehow and lockpicable, and it would be whole lot more funny
.. and it will make cars useless as it was
Apparently cars are lockpickable.
Booo. What was the reasoning behind this decision?