The same guard also checked if your dog was registered (I think my dog got a badge with his picture, although I think that was just for fun, and not functional)
And no easy ability to enter through side doors - you couldn't open a side door with your badge. At the time, you could still lurk outside a side door until someone else opens the door to exit. Eventually (11 years later) they locked all the side doors because they noticed people doing this sort of thing.
More recently, I think you have to scan your badge to leave so they can even track how long you're in the building, and know when you're supposed to work on site but you were there only long enough to have a coffee and then went home to continue working from home. This last part is second-hand knowledge since I haven't work there in a long time.