RE: Stepping in dog crap, pee, broken glass, gum, trash, etc...
Watch where you're going.
RE: Dirty feet...
This is a reason to bathe at the end of the day.
RE: Too many germs...
What doesn't kill you makes you stronger. (I have no allergies and very rarely get sick. I have no disinfecting products in my household, only soap and windex i.e. glass cleaner. Correlation is not causation, of course.)
RE: Kids with clean hands miss fewer days of school than kids with dirty hands...
Perhaps because their hyper-vigilent upper middle class mothers who are willing to spend lots of $$ on products that do the same thing as soap and hot water can also afford good medical care? Or they're paranoid that their precious sweetie will be at a disadvantage in the college acceptance race if he misses too many days in the third grade?
RE: Dirtier in America...
How many places in America have you visited?
Today there was a terrible rainstorm at noon, and as I walked back to work I got soaked, including my wonderful sandals

... I stayed barefoot at work for the rest of the day, and then I walked home barefoot. I'm still barefoot, and when I go to hang out with my neighbor in the garden tonight, I'm not putting on shoes.
And yes, I live in a city, albeit a small one.