Unfortunately a lot leaks in. Grapeskins are particularly porous for instance. So are most of the dirty dozen iirc.
Skins are healthy, but only if organic and/or clean fifteen.
But peanuts and white rice, the most common ones have already been 'peeled'
You need to rinse rice though, a lot of people don't realize that.
You do that to get the starch out and get a better result don't you? That's what I rinse my rise for at least
You don't "need" to. It just achieved a culinary effect
The culinary effect of not serving dirty food.
both a culinary choice (do I want sticky or non-sticky rice) and rinsing off contaminants (who knows who/what urinated on it even if only microscopic amounts are left, seriously)
In South Korea (where I used to live for a while) it's quite common to wash fruit with soapy water at home before eating them.