The counter is the smallest part of a bookshop's revenue
Walk-in browsing pays the rent on a good month. The money that decides the year comes from work that happens away from the shelves: booklists supplied to schools before a session starts, reference titles supplied to a college library against a purchase order, sets assembled for a coaching institute, and titles ordered specially for customers who could not find them anywhere else.
Every one of those has a date somebody must act on, a person who owns it, and a competitor who will happily supply instead. None of it appears in inventory software, because none of it is stock — it is follow-up.