British & Australian/New Zealand Electrical Standards would be a good place to start.
Good for them. Perhaps in those countries more things are grounded. But there's nothing about it for American electrical standards. Perhaps this is one of those things where it's only unsafe in those countries, just in the way some things cause cancer, but only in the state of California.
Of course, all silliness aside, those countries are 240v, correct? Their electrical standards are totally different from ours in many ways - so it's not a good comparison. The 240v system is inherently more dangerous, so things were created (like sockets with integral guards, fuses in the plugs, etc) that just plain don't exist here.
Apart from the risk of the chassis becoming live, there is also the possibility of leakage currents between various devices adding up and causing injury. I once heard a story of someone who had a number of VCR's connected together for tape duplicating and they'd removed all the earths because they were causing interference on the video.
They ended up getting a very nasty shock and had to have an expert come in, re-earth the VCR's, and isolate them with some isolation transformers.
OK, and here is an example of "doing stupid things to it". Taking a device that was designed to be grounded, and ungrounding it. In a device that's designed to be grounded, there is usually a capacitor to ground to filter out noise. Remove the ground connection, and yes, there could be some kind of leakage currents, severe if the capacitor is bad. I've been bitten by just such a device. But if the device was never intended to be grounded, then what's connected to the chassis? Usually signal ground. Signal ground - the same kind of exposed ground that would be around the outer shell of an RCA socket.
If nothing on the hot side of the circuit is directly or indirectly connected to the chassis, then how are you going to get shocked by it?
You clearly need to educate yourself further on electrical safety. It is not a matter of "stupid things being done to it", connections can and do fail, and current does leak.
As do you. Also, you need to educate yourself on the way things actually exist, in the real world. Take a look at a VCR. It runs on 120v, has a two conductor zip cord that enters the back (metal) panel of the cabinet and is secured by a plastic strain relief. It terminates in a two contact female plastic connector, with the metal contacts safely inside. It plugs into a connector on the power supply board, the bottom of which is covered by a thin sheet of plastic, and the board is bolted to the metal base of the unit. There is absolutely no way either side of the AC line is going to connect to that metal case. You could throw the thing down a flight of stairs repeatedly and it still wouldn't happen. OK, so, the plug pops off the board - it's still not going to short to the case. The mounts for the board could bend, and the board could touch the case - but it won't, because there is a plastic guard there.
The only way you could EVER connect the hot to the cabinet would involve taking the thing apart and messing with the wiring, removing the insulation, or something. Or, I suppose, you could manually break the strain relief out (not easy to do), then sit there grinding the power cord against the inside of the now unprotected metal hole in the casing, and wear through the insulation... But all these things would fall squarely into the category of "doing something stupid with it". They're not going to happen unless you do it intentionally. But you could do exactly the same sorts of stupid things to a grounded appliance, by breaking the third prong off the plug and messing with the wiring, or plugging it into a miswired outlet.
I still maintain that with proper insulation, devices with metal housings are perfectly safe to exist ungrounded. I mean, if you don't trust insulation on wiring or connectors, then every single power cord or in-wall power line is suddenly suspect.
But, grounded or ungrounded, there are plenty of ways for wiring to be botched to make anything unsafe.
-Ian