The problem is one person's abuse is another person's "I paid for it so I'm going to use it", or something along those lines. I would concur that the guy parking his car at the supercharger all day is wrong, and shouldn't be allowed. I also agree that superchargers are not to be a replacement for home charging. People using them as such, and there are active members here who openly admit to doing so, are the very example of selfish\entitled people. If you can't charge at home or at work, then don't buy a Tesla, that's my take on it. I can promise you that I'd be livid if I was traveling and had to wait on a supercharger spot for some local who simply didn't want to charge at home, and I'd have no problems venting my frustration towards that individual if I ever encounter one.
As to the solution, I really don't think there is one, especially now. Even if Tesla was strong with sensible, consistent, thoughtful, and articulate customer communication I just don't see how you single out people when you're advertising something different. Someone had the idea of restricting supercharging rates for anyone with an ownership address within 100 miles of the supercharger, I don't see how that works. All that's going to do is cause people to hang out there even longer and is likely getting into a legal issue, as well as, unnecessary customer angst during abnormal situations.
There really is no good solution to this issue from Tesla's perspective. Remember when Elon dropped the hint during the shareholders meeting (IIRC) and then the subsequent email went out and some people seemingly lost their freaking minds? I think that was Tesla's attempt at corralling this and it simply didn't work and really couldn't work. The only way Tesla could start to move the needle on this is to officially change their advertising and public stance on this issue and slowly grandfather in existing owners but I think if you're Tesla that's more of a PR nightmare than it's worth... Not to mention those who are litigious in nature causing Tesla grief legally...
It'll be interesting to see what Tesla does with the Model 3 and how it chooses to change\alter\update it's supercharging message to those buyers, if they change anything at all...
Jeff