auto-industry, should set up code/standard for bumper,
1."bumper position" must be same heights from ground, regardless truck or compact car;
2. the bigger/heavier car, the softer bumper,
e.g., bumper can be made of spring & solid rubber or pressured tire... for truck, bus & heavy SUV
it's easy to category by weight, 0.8, 1, 2 tone...
it's easy to set up a "bumper CODE/standard"
BTW, actually softer bumper will be good for self,
to absorb impact, in case of hitting pole or tree.