This sign, No Footwears Beyond This Point (Straits Times, 12 October 2009) is obviously wrong — but so also is the analysis of footwear as ‘generic, collective and plural’.
First, in grammar, generic is a term associated primarily with pronouns, not nouns. Generic pronouns are those referring to no specific addressee, like you and one, e.g. You/One should never work too hard. It is not clear what a ‘generic noun’ is supposed to mean.
Second, footwears is not a collective noun; it is uncountable. Uncountable nouns include flour, sugar, salt, bread, patience, food, tea, coffee, metal, furniture, equipment, information and software. They take determiners such as much and less (rather than many and fewer). Uncountable nouns do not (or do not usually) have –s plural forms; hence, *informations and *flours are wrong.
However, some nouns that are normally uncountable also have countable uses, with the meaning ‘varieties of’. So we may say I want some coffee, but also I have tried some of the world’s finest coffees.
The third point about footwear being plural is also wrong. Uncountable nouns are in fact grammatically singular, hence The information/equipment/software/furniture is not very useful; Coffee/Sugar/Salt is bad for health when taken in excess. And, of course, Footwear is prohibited in the prayer hall.
In Singapore, collective nouns are surprisingly often confused with uncountable nouns. This is perhaps due to the misinterpretation of the term ‘collective’ as referring to collections of, for example, shoes (footwear) and tables and chairs (furniture). Note that collective nouns refer to groups of animate beings (see previous post) — those with powers of volition, i.e. the will to act. This will to act enables members of the group (e.g. flock, family, committee, staff, crew) to act as individuals or as a single unit, in unison with the rest. Footwear and furniture are not collective nouns because shoes, chairs and tables do not have powers of volition.