My daughter runs cross country and track in high school. She complains of aching feet. She has been told before that she has falling arches. Will inserts in her shoes fix the problem, if she will wear them all the time? It’s summer time, and she likes to wear flip-flops. My guess is that flip-flops don’t help.
Flat feet can cause foot fatigue and/or pain. Shoes with a good arch support can be helpful – most good tennis shoes and running shoes have these. You are correct that flip flops and walking barefoot don’t provide any arch support.