Found a contradiction that I don't understand. From rule 1:

    # GOOD
    GET /products   # get all the products
    GET /products/{product_id} # get one product
    
    # BAD
    GET /product/{product_id}

But then in Rule 2:

    GET /shop/{shop_id}/listings              # normal, expected

Shouldn't that be "/shops/{shop_id}/listings"? Or is it plural only if you can actually GET the path (i.e. there's no GET for just "/shop") and otherwise it should be singular?