Why Are Aussies So Hated?

It is a good idea, but only as secure as the weakest link- which in this case would be the people using it.

For example- I swipe my card, open the door. There is someone behind me with a bike who catches the door as it swings shut.
They come in after me and are locking up as I leave.

Except they aren't- they are leaning up the beater they came in with and stripping the lock off an expensive bike which they then leave with.

It really depends on whether such a system is well-managed. Problems like this can be overcome.