Instead of having words that are only understood by speakers of one language, they choose icons that aren't understood by any.
Yes, that's the obvious reason for it, but having a reason doesn't make the icons any more comprehensible. Good luck using those appliances if you're a visitor who doesn't have the manuals and hasn't learned each manufacturer's unique iconography.
For better or for worse, English is a lingua franca in the EU. (Sorry, France.)
That's depends very much on age, class, geographic location. Someone could have grown up imprisoned behind the Iron Curtain, hence learning Russian as a second language. Nonetheless they deserve appliances, websites and infrastructure which they can use and understand.