They rarely actually own the cars they use, so not a lot of point. Tags are often used normally when someone gets early release from prison.
Tags are virtually useless any way. My next door neighbor was 'tagged' for 2 months. It made no difference to him going out. The only way they can check is to send some one to the house where the 'taggee' is supposed to be living.They have a 'detector' that looks like a mobile phone, it picks up the signal from the tag and tells them if the person is there or not.
It is rare for a tagged person to actually get checked, they only checked once on my neighbor. They don't even knock on the door if they do not get a signal, just report it to the police who are always too busy to do anything.