As [email protected] says, it's just a matter of simple isolation, like some 13 amp sockets having a switch and some not.
Nothing to do with "that lot from the EU", in which, I would point out, the UK is fully represented. They are much more relaxed about electrical safety than us.
Never saw a fused plug in the whole 7 years I lived on the mainland, and by far the majority of appliances had two pin plugs which could be inserted either way, with earthing being provided by a spring contact, like a car lighter socket plug.
This means, of course, that there is always a fifty fifty chance of the whole appliance being fully live, not just between the switch and the mains, simply looking for an earth even when it is switched off.
However, since they are, in the main, a lot more sensible than the average Brit, they don't get too many fatalities.
..... " Because it completely isolates the unit from the power supply, whereas the usual on/off buttons found on such appliances don't. "
I understand that but again WHY ?
I switch off our TV on the front but never switch it off at the wall orunplug it unless I am going to move it or work on it. The same goes for my PC but that does go through a 'master' anti surge unit with switches for PC screen extra plus a master off switch. Never switch it off at the back.
There may be different reasons for different units - but here's some.
In a VCR - if you switch the mains off, there is no power to the tuner - so aerial signals that feed through the tuner, get no or very degraded pass through. - if you switch the mains off, all the timing/programming memory will get lost, including the clock on the front.
In a TV - if you switch the mains off, you need to get up from your chair to switch it back on again (!!).
On a PC - it's useful to switch to a low power mode and/or standby, to enable fast switch on again.
On many domestic appliances - you would lose the clock display - cookers, microwave ovens, etc.