The reason those geographical clauses are in those contracts is because many states have ruled that non-competes are illegal unless they are limited in some ways to be "reasonable", and one common way states courts measure this is by ensuring that they are limited to something that might be a reasonable 'business area' that the company competes in. Corporate lawyers typically write in the exact radius that state courts have historically enforced into their non-competes to avoid them being disqualified for being too broad.

"Interstate commerce" on the other hand, just means any sort of business activity that crosses state lines. Basically every business engages in interstate commerce, just because commerce requires many interstate activities, like using the internet, or accepting electronic payments, or ordering supplies made in a different state.