@joefromchicago,
Well, I'm not sure if you want to discuss a practical solution for a real-world problem, or if you want to discuss the principle of it.
If you want to discuss the practical issue, I say have the condo association put a meter on the joint outlet. Then have the members check in and out as they use electricity. Alternatively, shut off the meter and force the owners of electric cars to run extension cables from their private outlets. Whichever is cheaper.
If you want to discuss the principle, I say that shared resources will be used unequally. Electricity is no different in that regard than all the other shared resources a condo offers. By joining a condo association rather than buying their own houses, members have agreed that they can live with free-rider problems like that. Quitchabellyaching.