I certainly hope the soap rinses off completely. I've used liquid soap to wash dishes, glasses, and everything I cook and eat/drink out of my whole life - maybe I've been injesting soap residue for over 30 years? :(
I would think that liquid soap is designed to rinse clean, as long as you can rinse it all off a non-absorbant smooth skin surface - like on a green pepper as opposed to a food that would absorb the soap and prevent full rinsing.
Consumer Reports recommends using liquid soap to wash produce. The USDA and FDA recommends using plain water. IMO plain water just doesn't work well at all. I don't really consider any of these sources credible though.
Do "natural" cleaners like vinegar or salt actually clean as well as liquid soap?
I hope others can chime in - I certainly don't want to propagate bad information here.