Tiff,

Reference the air bags, was the engine running or the ignition on at all?

If not then the car will probably have thought there was no one in the car.

Also, slow speed accidents may not trigger airbags. Or at least not the forward airbags. The car was obviously not moving as it was parked up so it may not have triggered because of that.

I recon the main reason behind why they didn't go off is because the ignition wasn't on.