Amazon discount codes working only for some product categories

Amazon has restarted selling online mainly in June and offered discount codes for a variety of products. However these discount coupons are only applicable for specific products.
For example the business discount coupon was not working for file folders purchased in bulk.Many business owners keep a lot of documents, papers for calculation,financial information and they require folders, yet the discount was not offered.
Also it is noticed, that there are fewer sellers on Amazon at present, there are very few deals of the day, compared to the pre-lockdown era, when there were a very large range of deals daily. It is a good opportunity for those who have no other work to start selling on amazon, plants and handmade items are the cheapest items for selling online.