26 people want airplane seat armrests that have enough room for my elbow *and* my neighbor's elbow.

Whoever gets into the seat first gets the arm-rest. Sometimes that means people don't get an armrest for the whole flight (for either arm), and sometimes it means people steal yours when you get up to go to the restroom. It's uncomfortable to not have an armrest to use. Why can't the armrests be wide enough to accommodate both elbows?