Certainly, it'll only wash off surface stuff.
So, IMO, what we have here is:
- rinsing fruit is probably not a bad idea, though the jury's out on just how much stuff there might be on the surface that you wouldn't want to ingest (then again, surely you'd want to wash anything that's been handled by the public)
- water's fine, but any type of soap will have a detergent/emulsifier that will work on substances that water does not, such as oils
- generally, no one soap is better than any other, there's no magic ingredient
- perhaps the only advantage of food soaps is that they're odorless/tasteless