Ok that's a given fact.
The legality of the driver doesn’t mean much.
It means a lot actually it does. Several points to make. He had no license thus should not have been driving any vehicle on any public road. He had no insurance thus the victims family is S.O.L. and left without income or justifiable compensation including the other passengers bills and loss. Had he stayed home in good old Mexico and came here legally, abiding by our laws, acquired a valid drivers license, liability insurance, etc then he would have been held to the minimal legal standards everyone else in this nation but an illegal aliens are held too. Now after posting bond he can skip town with new identity waiting at destination or go home to Mexico and come back as a different name. Repeat next accident. It's happening way too much in everything from car accidents to murder.
Eighteen wheelers throwing a recap would kill you well enough.
Indeed they can and do. That is why the drivers besides specialized licensing must first before getting on the road do a Pre-Trip Inspection and sign a legally binding sworn statement of having done such plus the trucks owner must carry carry liability insurance.
The point I was making is a wheel can come off a vehicle regardless of the identity or status of the driver. The other points you have are valid and form part of the reason we need to lock down our southern border.