My mom once opened the wrong '89 Dodge Caravan when grocery shopping in the early nineties, and it wasn't until she got in to drive that she realized it wasn't hers. She said the seat was too far back and then she actually stopped to look around. She said she had simply assumed it was hers since the key worked.
Depends on the manufacturer how many unique bittings would be made. I believe ~1000 was common. So pretty low chance but high enough a few people have stories here or there.
