I'll weigh in on the flip-flop scene. I wear them at one point or another on a daily basis. I have several different pairs in different colors by L.L. Bean with an arch support. I live in them. I reside in a subtropical climate in southern Florida and live on the water where the temperature right now is in the mid 90's and during the winter months the temperature varies; but most people around here live in their flip-flops. In fact, it is not uncommon for people here to wear flip-flops year round. No, can't wear them to work of course.
Flip-flops, called "sandals" here are all about what area one lives. I lived close to
@CatherineofAragon at one time. While there, I didn't wear them. I also broke both my ankles and feet wearing heels to the point that I can no longer wear heels due to the risk of tearing the screws out of my feet. God knows what god-awful shoes I'd have to wear if I lived there now. Boots, grandma shoes, and sneakers year round I suppose.
In hot climes, everyone wears them. Women in high heels at the mall or sitting on the restaurant patio look foolish here unless dressed in work attire. They're often referred to as "hookin' shoes" in this area if they're high, flashy, and worn at a place that calls for casual attire.