[nybble41]

Where I live, lawmakers and police openly admit that 10-15 mph over is perfectly fine, and expected.

Unfortunately, assurances from lawmakers and police are worthless unless they're written into the law. No matter what they might say, you're still open to legal liability for going even 1 MPH over the posted limit. Worse, this attitude makes the problem more difficult to fix—once they get everyone used to going 10-15 MPH over the posted limits they can't very well update the signs with the real speeds since that would lead people to think they can go 10-15 MPH over what the new signs say.

Selective enforcement results in injustice. Any law which is routinely broken without penalty should be considered null and void. Either set the limits properly and enforce them strictly, or do away with them entirely.