What you're describing is a situation where artificial speed limits have been applied. Most people (95% according to the stats) drive at the appropriate speed for the road, regardless of the signage. The few that deviate cause problems.
Honestly, in the US in a lot of areas, the school zone is bogus. In the suburbs where I live, in today's "helicopter parent" if my kid doesn't take the bus I'll pick him up in an SUV world, I never see kids walking when the lights are on. Downtown in the city may be a different story. But up here in the 'burbs school zones barely even make sense.
Honestly, in the US in a lot of areas, the school zone is bogus. In the suburbs where I live, in today's "helicopter parent" if my kid doesn't take the bus I'll pick him up in an SUV world, I never see kids walking when the lights are on. Downtown in the city may be a different story. But up here in the 'burbs school zones barely even make sense.