Speedcameras only exist to make profits. Good road design is what actually lowers speeding. Any road where can be sped is either badly designed or has an artificial limit, either to make profit or because the council has absolutely no clue what they are actually doing.

I’ve driven in the Netherlands and it’s amazing there. Almost all road infrastructure in cities and towns is designed to not have speeding issues, yet still have a good flow of traffic. (The only stupid speed limits there are those on the highways)