Sadly, this etiquette (or lack therof) is not uncommon. I can't count how many times I see EVs parked in the charging stall without bothering to plug in as if it's special VIP parking to which they are entitled. At least plug in to make it look like you're there for a reason! That kind of attitude is what leads d-bags to park their ICEs in EV stalls on occasion. And the people who suffer are those who truly need the charge. (Thankfully I'm lucky enough to charge at home, but I sympathize with those who don't have that option.)
I think the solution is to put the EV stalls in the middle or far end of the lots to dissuade people who don't need the charge from using them. I know it may require more cable and conduit, but it would ensure the "special" stalls are serving their intended purpose. That should keep the ICE vehicles out too.
**stepping off my soapbox**