This, it appears, will be yet another sad story on the roads this holiday season. From what OP has written and not knowing the exact geography of the incident, it appears we have essentially an off road vehicle crashing with an on road vehicle in a location where such an event is avoidable for whatever reason.
Personally, I am very much against the uncontrolled use of essentially off road vehicles on the roads in some of the tourist zones in this country for the simple reason that driving on highways and interacting with road traffic at very best is a very risky business indeed. This has been confirmed this past week by the fact that DR is the deadliest place to drive on the roads in the western hemisphere.
Unfortunately the tourist wants their thrills and businessmen in tourist areas rent off road vehicles, and from what I have seen and heard the training and advice given by 'some' renters is poor. And mixing in with regular traffic is a recipe for disasters. Was it not last week that someone wrote about the son of a prominent person on the NC being killed on an off road vehicle?
The OP may cast blame on MOPC for the wrong reasons. Imo MOPC should not be allowing off road vehicles to travel on highways without more stringent controls. Not sure if it is in MOPC's remit to control traffic as suggested.....I believe that is AMET.
Equally, I suspect driving on sand beaches is off limits to off road vehicles in DR so perhaps greater overall control is an issue here.
Don't blame the OP for moving on. There are times one can help and others where an added onlooker serves no purpose.