There are no laws or regulations in the United States regarding motorists driving with bare feet.
Here is a link to a response from 40 states, in 1994, to a letter asking if there is any laws against driving with bare feet. The answers are in alphabetical order by name of state.
In the two or three times, I have been stopped by police, and came out barefoot, none of the officers ever mentioned anything regarding my bare feet.
click for the link