In most western countries it is the driver of a vehicle , not the owner who will be held responsible for a traffic violation. This is why photos / witnesses of the violating driver are required.(e.g.running red light, exceeding speed limit or even accidents).

How is the law in Thailand? Can the owner of a vehicle be held responsible for the misuse as long as all reasonable precautions were taken?

yes

I think you will find that normally the owner of the car is responsible, unless the actual driver can be established. That goes for most countries, including Thailand.

If they flash the car when running red light the owner gets the fine send home for that, only when the police stops the driver for doing this will the actual driver receive the fine. It's a question of presuming that the owner drove the car, unless proven otherwise.

At least in Germany the law accepts that a vehicle can be used by several drivers. If a family has 2 sons, each with valid drivers license, and a fatal accident occurs, the owner of the car, the father , cannot be held liable, if there is not proof beyond reasonable doubt that father indeed caused the accident .

Same with a rented car where 2 possible drivers are noted in the rent contract, of course the car rental company is not liable, assuming no witnesses who of the 2 drivers, who were not harmed in any way, will be held liable-- ???)

Does Thai law really hold the proprietor liable for any damage caused by his property even when the question of fault cannot unequivocally answered?

When the young Hi-So girl crashed into the van on a Bangkok Expressway a few months back, she had no licence but got off scot free, didn't she? The owner of the car was refusing to turn up at the police statioin for quite a while afterwards. So, depends on who you are in some cases, nothing to do with ownership

ordinary law for Thai citizen ??

Responsible and Thailand don't really go hand in hand.

I think you will find that normally the owner of the car is responsible, unless the actual driver can be established. That goes for most countries, including Thailand.

If they flash the car when running red light the owner gets the fine send home for that, only when the police stops the driver for doing this will the actual driver receive the fine. It's a question of presuming that the owner drove the car, unless proven otherwise.

My understanding is, as you say, it depends of the offense.

If it's a light offense with only a fine to pay, the owner is responsible.

Now if we are talking about a more serious offense, usually involving jail time, the actual driver has to be identified.