"Same as with taxis, and I think that it is also a safety concern." quoting myself.
I was talking about physical safety in case of a crash. In many (all?) U.S. states, after a child "graduates" from a car seat, she or he must sit in the back seat until they reach a certain age (maybe 12 in some cases, trying to remember what it has been for my grandkids), with seat belts on of course, because passengers in the back seat are less likely to be injured in a car accident. I suppose those of you who reference the safety of the passenger relative to the driver, and vice versa, also have a point.