If any of you knows why we say, "shoe shop" not "shoes shop", could he or she tell us? It would be more appropriate if he or she mentioned the resource on which he depended. Thanks in advance

When two nouns followed by each other , the first one is an adjective to the second one .The adjective has no plural form.

لانها صفة يا محسن مثل a ten-year اخيك رماح قصدى

Hello Mr Muhsen
singular and plural : noun + noun

first noun singular: shoe shop
In noun + noun structures , the first noun is normally singular in form even if it has a plural meaning

a shoe shop (= a shop that sells shoes)

a toothbrush (= a brush for teeth) trouser poc/cets (= pockets in trousers) a ticket office (= an office that sells tickets)
exceptions
Some nouns are plural in this structure. These include nouns which have no singular form (like
clothes), nouns which are not used in the singular with the same meaning (like customs), and some nouns which are more often used in the plural than in the singular (like savings). In some cases, e.g. antique(s),drug(s), usage is divided, and both singular and plural forms are found. In general, plurals are becoming more common in this structure. Examples :
a clothes shop
a drinks cabinet
a glasses case
a goods train (British English)
a customs officer
a sports car
arms control
a greeting(s) card
a savings account
an antique(s)
dealer/shop
the accounts department
the drug(s) problem
the sales department
the arrival(s) hall
(at an airport)

the outpatients department (of a hospital)





Source: Practical English Usage, Michael Swan Page 524

Best regards to all those who answered my question. In fact I was asked this question at school (by a colleague) and I gave an answer that is similar to what you have told me. Yet, I wanted to be sure of my answer, and I also promised that colleague to try to find a complete answer. And here I am, got it from you, so all my best regards to those who helped

Great thanks for all