Those regulations exist, enforcement is the problem. Fatbikes are the main culprit here. They are sold within legal limits, but it’s incredibly easy to just remove the software limits and/or flash custom firmware.
Police does regular checks, but people tend to quickly turn the limit back on when they see an officer.
Kinetic energy is exactly what’s harvested, which is why modern wind turbines are not far off the theoretical limit of the amount of energy that can be extracted. (Betz’s law)
By taking energy from wind, you slow it down. Slow it down too much, and it can’t get out of the way in time for new air.