Washington State also has a law that requires the use of a dive flag for shore diving. Except when conducting classes, we ignore it ... towing a dive flag can be hazardous to your health.
A couple years back I watched as a large (45+ foot) boat plowed through a popular dive site at over 20 knots and ran over a dive flag. The flag was in 20 feet of water, and there was an OW class being conducted directly beneath it. The whole thing was captured on video, and the boat owner and operator was easily identifiable, as he lived in one of the expensive waterfront condos just a few blocks from the incident.
When we reported it to the Seattle Harbor Patrol, they told us there was nothing they could do about it unless the guy hit and injured somebody. As the officer explained "no law was broken". Of course, deciding that it's safer not to use a dive flag is, in fact, breaking the law ... go figure.
... Bob (Grateful Diver)