Because they bought the most dangerous tool we have in common use, and society decided to make the law.

The owner isn't responsible for the drivers actions, but they are required to name the driver. (Or declare the car stolen etc.)

(At least in much of Europe.)

I would say they could be, but its needs to under strict circumstances. Easiest is with guns, I loan you my gun knowing your going to go and use it to commit a crime, but that is covered under being an accessory. With cars, the only situation I can think of is if you loaned your car to someone you knew was drunk and was going to drive. Or you loaned me the car knowing I was going to use it as a get away vehicle in a bank robbery. But I assume the second case would also be covered under being an accessory to the crime.

But for the purposes of traffic tickets, yea, its ridiculous. It also has a lot of faults. I got a traffic ticket from a red light camera for a car I owned when I was stationed in California. The ticket came to me in Oregon 5 years AFTER I traded that vehicle in (I traded it in right before moving to Oregon) and the traffic cam ticket was from Texas, a state I've never driven a vehicle in. My only presence in Texas has been being in the airport in Dallas. The ticket was also for a year prior to when I received it. So I hadn't owned it in 4 years when it ran a red light in Texas.