In Italy several cities lowered the maximum speed from 50 to 30 km/h.
There was a huge fight over it, car drivers in those cities were mad. Plenty of politicians opposed it.
One year later stats were super clear: streets got way safer and the number of fatal accidents dropped to near 0. Time to traverse cities didn't change much, as it was already limited mostly by traffic and lights.
I think this ignores the argument the high speed limit people make which basically boils down to "sure some people will die or get injured but its worth it because driving faster is fun"
There was a huge fight over it, car drivers in those cities were mad. Plenty of politicians opposed it.
One year later stats were super clear: streets got way safer and the number of fatal accidents dropped to near 0. Time to traverse cities didn't change much, as it was already limited mostly by traffic and lights.