No brainer?
Today it's few level 1 power stations that any existing buildings electrical system can handle, and minimum cost to the building owner. In a few year, how many EVs will be on the road and pulling up at a WDW Resort or Theme Park? Buildings aren't designed with that much capacity in their electrical systems, in fact the electrical grid as a whole isn't likly to be able to handle it.
Most owners have a small slow charger at home.... something like 3KW that might get them 100 Miles after 8hrs of charging. Newer commercial 150KW rapid chargers (most older EVs can't handle, but new ones will) can get you 100 miles in 15 minutes. Of course a new Level 4, 150KW charger uses more power than the average home is designed for, and even most commercial buildings don't have that kind of spare capacity. Then too the technology is still changing, where will it be in 5Years or 10Years? Maybe 300KW chargers, or will each car have it's own "Mr Fusion"? In the end Disney has to look at what it is going to cost them to offer this service, how long it will take them to see a return, and what the risks might be.