Inefficient road usage (not making the most of our roads!)

I've noticed a few drivers don't follow golden rules of keeping traffic moving on normal A roads and even motorways recently:

• Not driving near the national speed limit (60mph). Trundling along at 40mph creates a tailback with often no safe overtaking spots. Solution: Drive the same speed as everyone else, like they do in the US, an evenly spaced convoy ;)
• Speed cameras and traps, at fixed locations and fixed speed limits delaying traffic 24hrs a day when they only need to rate-limit traffic during rush hour. I've been on dual-carriageways which are empty at midnight, still with a 50mph speed limit. Likewise driving past a school in on a Sunday is still a 30mph zone!
• On motorways some drivers forget to move back to the slower lanes when they've finished their overtaking manoeuvre. On four-lane motorways I see people trundling along lane 2 and 3 at 65mph, which bungs up the fast-lane with more traffic than the rest of the road (undertaking not being allowed!).
  

What's the solution? I think just a little bit of common sense, and polite reminding of those making the mistakes. Variable speed-limits which depend on traffic levels, like we have on motorways. Speed cameras can be replaced with interactive speed displays, with the polite "Thank you" when the driver slows to within the limit ;)