Are there technical means to enforce aircraft speed limits as well as regulatory means?
Some aircraft have flight envelope protections which, among other things, aim to prevent the aircraft exceeding a predefined maximum airspeed.

High Speed Protection:
Prevents exceeding VMO or MMO by introducing a pitch up load factor demand.
The pilot can NOT override the pitch up command.

- AirbusDriver.net
Note that these are structural safety limits, people on the ground cannot use this feature to impose arbitrary speed limits by geographic area, time of day etc.