People with manners use their hands while sneezing or coughing, people use their hands everywhere to hold on, open/close doors/windows, hit switches/buttons/keypads/... touch wares in shops, pay with used money, etc. they scratch themselves and some even shake hands. In other words, people use their hands to collect the germs of an unknown number of other people and washing alone dont disinfects them.
On the other side, except for bowlers most people only wear their own shoes, many use socks or nylons and shower a few times each week...especially before they have (planned) sex. In other words, only those who run around barefoot in public areas collect other peoples germs with their feet and every sexpartner is someone you already decided to share germs ^^
So except for hydrophobic pigs everyone has cleaner feet then hands.