> Too tricky for international flights.

So how do most European airlines have just that on their intercontinental flights?

I don't think I've flown intercontinental without universal power sockets (accepts EU & US plugs, sometimes others, voltage info hard to find) in the past 10 years.

In some cases it's sadly still a premium cabin thing. I refuse to fly economy at this point, premium eco tends to be good enough to get power sockets.