Wait, how long has this been going on? Do most people really take showers every day? Most people I know (myself included) only do it when they get smelly/sweaty, which is roughly every day in the summer, every 1.5-2 days in the winter. Is this a US thing?
I guess this is one of those cultural things, and people just do it half because it's good sense and half because it's the custom.
South African here. I shower daily, no matter the season (as does everyone I know). Sometimes another quick shower just before bed on a hot day.
I just don't feel clean otherwise. Climate accounts for the seasons, but we do it in cold-ish Winters as well.
I think there's a distinction between hygiene and social/cultural 'etiquette'. I will always make sure I am very clean before meeting someone, casual or otherwise.