Actually, there are no written rules prohibiting monks from driving.

He might have been drunk, there's a rule against that one

Careful guys! We will be accused of "thai bashing"by the falang/thai luvies if critical like this. Although the "bashing" seems to be going on the roads without any foreign assistance.

a tragic accident ? the car veered out of its lane it sounds as if the monk was asleep at the wheel or there might have been another reason a post mortem is the answer .