Keep in mind that, and my apologies if I missed it, the garage may fill up by the time the car is done charging. If the garage is full where else is the person supposed to park once their charging is complete? It's quite common here in the few garages that have charging in them that they will fill up so where are you supposed to go when your car is completed charging? If you have no place else to park, say what you will to me about it, I'm not moving my car.
Granted with my Tesla I never even use the garage EV spots around here anymore since most aren't free and have time limits that are enforced so the risk of not having a place to move my car to outweighs any perceived benefit to charging.
The problem, IMHO, isn't the drivers/owners, it's the lack of charging infrastructure to meet demand. I'd say focus your efforts on that...
Jeff
You certainly will move your car once charging is complete, else it will be moved for you (towed). That's the policy already in certain SoCal corporate garages and of course in Washington State. Although in fairness in WA they'll probably just write the $125 ticket the first few times. These are not parking spaces. They are charging spaces. Analogous to gas pumps. Park at one of those at a busy SoCal Arco location and see how that goes over.
Private property edge cases aside, how often have we already seen prime charging spots at movie theaters, Costcos, hospitals, and yes, even time-restricted popular garages saturated with cars that quite probably aren't charging? At first at one corporate garage in SoCal, the charging spaces were hogged by hybrid owners milking their 11 miles of electric charging for all it was worth (and then squatting all day). A couple of policy changes (see towing above) put the kibosh upon that behavior fairly quickly. Whether a for-profit garage even cares is another story entirely.
There's got to be more to the equation than supply and demand. Enforcement and education being the two variables that come to mind. Similar to blue disabled spaces and red curbs, green EV *charging NOT parking* spaces will slowly permeate the (inter)national consciousness.
Then there was the Bolt owner who tried to charge at a supercharger location recently. The security guard wouldn't even let him park there for 5 minutes - gotta love it. Thing is, the Bolt owner had bought the car the night before and his salesman evidently said, "Oh, you can charge *anywhere*." Gah! Fortunately, there were some Clipper Creek J-1772s nearby.
Point being, this is the level of ignorance ^H^H^H^H knowledge that evidently serves as the lowest common denominator these days. See hybrid owners above for another class of short bus folks.
Supply, demand, enforcement, education, proper signage, and a lot of green paint would be a good start.
In Oregon, the EV spaces on private property came with municipal no parking signs paired with EV charging signs. And with managers who had NO problem calling their towing service for ICErs. The managers considered the EV spaces to be no different than red zones in that regard.
I suspect we will be subject to a patchwork of enforcement and non-enforcement for the next 5-7 years nationally. Then again, it only took a generation or two to get people to wear their seatbelts with any degree of consistency.