I think the answer is because Canon want to sell cameras ...
Imagine the scenario;
You are a sales person in a shop (nod to Robin)
The latest model arrives in store
That valued customer you rung up and got in specially to demonstrate and sell one to, arrives
You get the camera out of a sealed box and proceed to demonstrate
Imagine the first impression it would make if it wouldn't take a picture
Therefore I'm not that surprised by this default behaviour.
The mistake everyone is making is assuming that the manufacturer should put the customer first
OK, so the good sales person would have had a play first and learnt their way around and fitted a card before the customer arrives, but why risk losing a sale to an inexperienced sales person, perhaps not even in a camera store, but say, a department store and unfamiliar with cameras entirely.
Get my drift?
Cynical Dave?