Ah so elderly couple in Germany allows you to conclude that the whole of Europe showers less than your household, a household which is also representative of the whole American continent, did I get that right?
I'm sure like everything else, times have changed and Western Europe and the US are now more similar (if not the same) in their shower habits.
But I'd like to provide another anecdote just for fun, from 6 years of living in Spain beginning 20 years ago. It was, at that time, certainly considered unique to shower every day, in a mid-sized northern Spain city. Unless every other friend in my residencia was weird in this regard, which is unlikely.
Interestingly, they also had a communal pool. Swimming to them rendered a shower that day unnecessary. Note -- I didn't notice any notable signs of bad hygiene, though.
Anyway I'm sure there are studies that show we're all converging on similar routines!
Curious. I'm from a mid-sized northern Spanish city, always shower once a day, most of my family and friends do as well. People I know from the south of Spain even shower more than once a day (it's hot down there). And in Spain there is the meme that French and British people shower much less than the Spanish. No idea if there is truth to it (although when I lived in the UK, I was shocked at how seldom the British people I was sharing house with showered, but that's a sample size of two).
European innovation is doing quite well. As usual it's the part where we actually make money off the innovations where we suck. Good trolling effort though! ;)