"...But say it costs an extra $5 to prevent the device from catching fire, and the EU says "product must not catch fire", then you don't really want the cheaper version from outside the EU ....."
That's a relevant point.
I've mentioned before that I scuba dive on a rebreather. My particular one is made by a company called JJ.
In Europe you have to buy the CE version. Outside of Europe you can buy the non-CE version.
On the face of it they look identical. But the CE version, for example, has to comply to certain criteria such as the "work of breath" - how hard it is to breathe on the unit at various depths, in various positions.
But also, the CE version won't allow you to build the unit up incorrectly - the gas in a rebreather is in a closed loop and never leaves said loop. In order to keep you breathing, the unit analyses the oxygen content and tops it up as required, as well as scrubbing out the waste CO2.
On the non-CE units, there's nothing to stop you connecting the breathing loop on backwards*. This would lead to a build up of CO2 and hpoxia. It's bad.
The non CE units are considerably cheaper as they never have to be put through the same destructive tests that CE calls for (5 units, I believe, are all tested all the way to destruction).
In Europe at least, you can't buy one from the manufacturer unless you can prove you are trained on the unit - this may also be true outside of Europe but I am not sure.
*This may have changed since I got mine, but certainly was always the case.
So...I guess to contradict my own earlier posting, you are right to say that sometimes all is not actually equal, globally.