Is this actually an issue? Who knew.... :o
My DSs have changed their own beds since they were about 9 or 10 and I do ours mostly but even cack handed DH seems to manage without any hassle. I'm an inside out method person :) DSs used to hang it over the bannister as they found that easier especially for doing up the buttons.
My DM does rely on me or my sister to change hers now but she is 83 so can be excused. She also likes a 15 tog duvet and a flannelette duvet cover so that's not a combination to be recommended.... She can actually do it herself but it takes her all day as she can only do a little bit at a time as her poor arms get too tired :(