Cars have roll cages built into the frame of the vehicle. Thats why they don't crumple under their own weight if they roll. I don't know what kind of Mad Max wo

Cars have roll cages built into the frame of the vehicle. Thats why they don't crumple under their own weight if they roll. I don't know what kind of Mad Max world you're driving in but an external roll cage and a 4 point harness (as opposed to the 3 point harness already fitted in literally every car) seems like complete overkill for most use cases. Also motorway driving is generally the safest kind of driving, so while your story is certainly evocative I don't think it really justifies your claim that every car should have two roll cages. We don't put cow plows on most cars either, by your logic we probably should.