They do have some sheet metel behind the foam....But nobody ever hits anything at 5mph or less! My 1940 Plymouth has chrome spring steel bumpers and mounting brackets! Degraff is right when you see modern cars in a accedent there debris all over the road! And the cars are totaled most times!

I saw this just now -

Cars are safer than they ever have been, that’s indisputable. And modern bumpers, in the context of their role in modern collision-protection systems, are fantastic. They absorb energy, they take the fall so you don’t end up a custardized mass of people-pudding, and that’s great.

BUT

Bumpers have been swallowed up by painted bodywork, in service of both style and aerodynamics, so now the actual impact-absorbing bumper is buried behind thousands of dollars worth of painted plastic and metal, lights, grilles, and sensors. It’s like going into a battle with your shield held behind your ass.
Effectively, all of the expensive, painted parts bumpers were designed to protect are now exposed and vulnerable, even to the kinds of extremely minor mishaps that bumpers once laughed off with big, rubbery chuckles

That is certainly true.