it is just not your bottom that has germs. in a bathroom there are diseas-causing germs on every surface (the countertops toilet seat handles etc). while an extremely agile and careful person may not touch their genitals or anal area they do touch surfaces. contaminated hands spread germs to other surfaces and other people. washing hands is the most important and basic of all hygiene practices. only a fool would not wash their hands.
why should people wash their hands after using the restroom? . my child told me "i wipe with toilet paper not my hand. " i would like a proper medical response to give her so she fully understands instead of me just telling her to do it.