No need to cry in our beers, lament the downfall of society, or hope that Tesla (who lacks the staff to even answer phone calls about vehicle service) will act as a long-distance after-the-fact supercharger concierge and enforcer.
The best solution is buried in the middle of this thread: Keep a small notepad and pen in your glovebox. When you encounter this situation, leave a note under the offender's wiper blade.
You don't have to be long-winded, clever, or vulgar. For non-charging Teslas, just "Please don't park here unless you're actively charging." Adjust as needed for the situation.
In many cases, a gentle private shaming is good enough to change behavior. This goes for public (level 2) charging offenders, too.