memes

It's a real thing, road design has an inherent "natural speed" where most drivers feel comfortable, not too quick, not too slow. In the Netherlands if you get a speeding ticket there is a chance that you can successfully argue in court that the road design invited you to drive faster and get the fine annuled. When that happens the government will ask the company responsible for that bit of road to add traffic calming measures like bumps, or obstacles you have to go around that slow you down. Highways are an exception though.

As an addon, those private companies responsible for the roads have to abide by certain design philosophies made by the government, and they are legally responsible for the safety of the roads, if someone dies and it's found to be due to the road design, or its state of maintenance for example, they can be charged massive sums of money.

Most drivers with experience can tell by how a road is constructed (materials, bank angles on curves, etc.) roughly how fast they can safely go, and there's a subconscious mental tug to get up to that speed. Whether you personally are impacted by that or not, it's a well-known phenomena.

When everyone on the road, most far less thoughtful than yourself, are experiencing that mental tug, traffic moves naturally faster than the posted speed. And then that gives probable cause for our racist police to pick and choose who to fuck up.

It's more so psychology. There's a few videos floating around YouTube by creators like Not Just Bikes that explain the concept, but in short most people are going to drive a speed that is comfortable for them, and that is dependent on the size and design of the road, which means the best way to make people obey the speed limit is to use narrower roads and the best way to make people break it is to design wider straighter roads.
This is what they mean by the speed "speed limit being too low for the street". The speed limit may be an amount but the speed suggested by the street design itself pushes people to go faster