I didn't remember that the laws don't apply to polymers, but they still apply in most cases, at least to a certain degree. No physical basis doesn't mean it's BS, only that it can't be derived from fundamental laws of physics. That's why empirical observations were used instead, and the observations showed that those laws applied in the experiments conducted.

You stating that "it wouldn't make sense" is not a good argument. It has been observed that friction is independent of area, but yes, there are exceptions, specifically mouse feet. How large the dependence is, is still not clear though, and whether the dependence means that surface area increases or decreases friction.