"Opportunity charging" your electric car or stealing what isn't yours?

So, the good thing about electric cars is that there is an infrastructure already in place, right? These aren't the quick-charging units that can fill up your batteries in 30 minutes or less, but any standard outlet will at least put a little juice into your car.
Recently, Solar Dave found a Tesla Roadster parked at the Denver International Airport getting what he thinks was some free and illegal electricity. Whether it actually was illegal or not we're not sure, but Dave did say the car was parked in a somewhat hidden area. He also asks:

... let's say someone from DIA sees this right after the Tesla is plugged in and disconnects it. The Tesla owner then comes back a few days later to find he has not enough battery to get him out of the parking garage, and someone is there to make sure he does plug in again when he returns. What does the owner do? If he gets a tow truck where does the tow truck take the car? The nearest gas station I am sure does want him stealing electricity either. So does he get towed all the way home?

Our friends at Green Car Reports figure filling the Tesla battery from this outlet might cost $4.50. At the very least, the situation shows that parking garage owners should probably be thinking seriously about installing charge points to lure electric car drivers to their location and charge them for the juice. For now, though, maybe it's better to let things like this slide. As Marc Geller writes at Plug In America's blog:

When we consider the question of public access to electricity for plug-in cars, we have to consider the social benefit. If plugging in at the airport (or work or some parking garage or mall) allows you take your electric car rather than a gasoline car, we all benefit from reduced emissions and petroleum consumption. These shared benefits are great enough to establish "rules of the road" that encourage access to power for cars.

[Source: Solar Dave, Plug In America]