It can be questioned, not enforcing them isn’t questioning them and won’t make them change, if people disagree with the speed limit somewhere they can complain to the authorities responsible, in the meantime is still the limit and you’re breaking the law by not respecting it. It’s the same thing with every laws and is the reason why when they change, criminals don’t suddenly get released from prison because the law they broke doesn’t exist anymore.
Ever heard of the social contract theory?
Heck, what if I believe that school zones are bullshit and want to do 50mph in them and it’s the kids responsibility to act safely? Would you defend my right to drive 50mph because you believe I have the right to question the speed limit in school zones this way or would you tell me to address the right people and live with the current limits until they’re changed?