If you're a frequent flyer carry a small power strip like this one or this one.

I always carry a mini-power-strip in my carry-on, along with a 4-port USB charger and USB power pack. While I carry them primarily for me, and primarily for use at the hotel, I often will offer it when other travelers need them. AC outlets and power ports on airplanes are far more common than they were 10+ years ago, they still seem in short supply. Even when I don't speak a common language with another traveler, I've never been refused when I offer to share the already-in-use outlet.