Given time to properly
Given time to properly explain, the case can easily be made that there are germs present on the floors of many public restrooms, thus the reason to go barefoot into them whenever possible.
By the time you enter your car, home, or workplace, your bare feet will have been cleansed of those microbes.
Not so the other's shoes, which will further incubate those pathogens in the warm moist indoors.
Too bad TV and radio hosts always bring up the subject, but never really allow for a complete answer.
I'd like to see Oprah look directly into her camera (if that's what she does,still have never seen her show) and proclaim:
"I will NEVER wear a pair of shoes into a public restroom EVER AGAIN after hearing the good doctor explain this. Barefoot it is for me from now on!"