Snow plow eliminating one hazard but creating another.

I understand the need for snow plows to maintain a constant velocity to ensure they dont get stuck, however I believe they are doing so at the risk of private citizens.  Twice this week during light snow on the road I was almost hit by a snow plow ingoring a red light and a stop sign.
Are snow plows not required to follow traffic laws?  If so I believe they are abusing their authority because the condition of the roads did not support his actions.  Once he was only laying salt.