Complete agreement on store websites. Speaking professionally, even.
I do think there are a lot of cases where the distinction between mass and count nouns has become unclear, and others where it's just shifted from one to the other. Take 'data': by old standards, it was a plural count noun: 'fewer data'. That actually registers as ungrammatical for me, though, because it's almost exclusively a mass noun in my lexicon: 'less data'. (And the singular, 'datum', doesn't even exist in my productive lexicon.)
But aside from that, I do think there's been a shift in usage of 'less', such that for many native English speakers it has become grammatical to use it with count nouns. (The reverse has not happened with 'fewer': I don't know anyone who would ever say 'fewer water'.) If I had to guess, I'd say that this is due to speakers generalizing from 'more', which is used for both count and mass nouns.
no subject
I do think there are a lot of cases where the distinction between mass and count nouns has become unclear, and others where it's just shifted from one to the other. Take 'data': by old standards, it was a plural count noun: 'fewer data'. That actually registers as ungrammatical for me, though, because it's almost exclusively a mass noun in my lexicon: 'less data'. (And the singular, 'datum', doesn't even exist in my productive lexicon.)
But aside from that, I do think there's been a shift in usage of 'less', such that for many native English speakers it has become grammatical to use it with count nouns. (The reverse has not happened with 'fewer': I don't know anyone who would ever say 'fewer water'.) If I had to guess, I'd say that this is due to speakers generalizing from 'more', which is used for both count and mass nouns.