Sometimes car drivers have to slow down. Maybe on a big, straight street. Maybe on a state highway. Maybe on the main street in town. Even in those situations, if there is a crosswalk in regular use for most of the day, they've got to slow down. If they don't, the street must be changed until they do. That is the most important task a traffic engineer in small-town Utah has. It shouldn't take 15 crashes in 5 years to prompt that action. It shouldn't take an additional fatal crash with a child victim to prompt it.
Anyone who doesn't understand any part of this should never drive on public roads.
You can put all the speed limit signs you want on that street, but it doesn't change the fact that the road is too wide and straight and people will go the speed they feel comfortable at, regardless of the signs.
That street needs to be narrowed, have parked cars on the side, have speed tables, a boulevard, dynamic feedback signs, or other traffic calming measures. Physical objects and changes to the environment are what cause drivers to slow down in urban environments, not flimsy metal signs.
There have been numerous studies and research projects on this. Here's one by the Federal Highway Administration showing the effects of various traffic calming techniques in situations just like this one:
https://www.fhwa.dot.gov/publications/research/safety/08067/
You're preaching to the choir. All of that stuff is what I meant when I said "If they don't [slow down], the street must be changed until they do." I assumed there were already signs in place.
Anyone who doesn't understand any part of this should never drive on public roads.