If you have lower back issues, each speed bump is painful, no matter how
slow you cross it. Also, barriers can make a neighbourhood arms race -
street A gets speed bumps; traffic diverts to B & C, who get roundabouts;
traffic diverts to D & E, which get pinch points; traffic diverts again,
streets F, G, H & I become one-way; wash, rinse, repeat.
Here (UK) we have speed bumps that are narrow - cars hit the bump, buses ambulances and trucks hit the bump ... though cars in the US are pretty big, so not sure this would work.
The speed bumps that I've encountered in the U.S. typically take up as much of the street as possible. The UK example is interesting, but I think you are right about the cars here in the U.S.