Some time ago, around 2008, I let my friend use my bicycle for a few weeks. He ended up loosing a key to the bike lock, and I had to cut off the lock to get the bike out. So here I was, with an battery operated angle grinder, wearing a hoody, cutting a bike lock in the middle of downtown San Diego at 4pm on a weekday with streets full of people, 4 blocks from central jail, and cops going up and down the street. It took me 15 min to grind though the lock, and it made a lot of noise. No one even bothered to ask me what I was doing, people were walking by as if I didn't exist. Cops drove by without stopping.
My point is, if these machines were destined for public places, it wouldn't surprise me if a man in overalls could sit next to them and grind away epoxy with impunity for hours before anyone would think twice about it.
From the story, it sounds like the client actually cared about the security of these devices. I would be somewhat surprised if they were left unobserved long enough for someone to surreptitiously carve out the epoxy and attach a drive to it.
Though, we can't know if the client was looking for intrusion prevention, or merely after-the-fact intrusion detection. :)
My point is, if these machines were destined for public places, it wouldn't surprise me if a man in overalls could sit next to them and grind away epoxy with impunity for hours before anyone would think twice about it.