Are the power requirements the same? My assumption would be that usb wall chargers wouldn't have the juice to keep your laptop battery at a steady state, let alone charge.
The provided iphone wall charger is 5 watts, the provided apple laptop charger is 60 watts.
I suspect airport chargers are more like 1 watt, but the problem is whether end-users will hook their laptops up to the insecure charger, not the efficiency or lack thereof :)