People prefer to drive at the speed dictated by the road design. If it feels natural to drive at 60 km/h, people will do exactly that even if it is illegal. if it's a narrow cobble stone path with poor visibility, it feels much more natural to slow down to something like 20...40 km/h. The legal speed limit might be higher, but people just don't feel comfortable driving faster, so they won't.
In rural areas you can find some absurdly tight bends that have been there for at least a hundred years and were probably designed by cattle or sheep. The speed limit could be 80 km/h, but there's a warning about a tight bend and a recommended speed. You slow down to 60 km/h, but it feels kinda dangerous. You slow down to the recommended 40 km/h but it still feels uncomfortable. You finally pass the bend at 30 km/h and that felt like you barely made it.
Every now and then, you'll also find some fearless people, who usually end up wrapping their car around the nearest tree. They are immune to speed limits and only mildly resistant to good road design. These concepts don't apply to the people who are striving to win the Darwin Award, but they are still relevant to everyone else though.
This seems like the right answer. 😄