Hong Kong enterprises can print their own invoices, and after customers consume them, merchants will open bills with company seals or signatures as proof of entry. Invoices of big businesses are generally printed by machines, but handwritten invoices are also common in small private shops and restaurants. Some of these bills are called "receipts" and some are called "handwritten bills". Bills obtained in Hong Kong are usually invoices and can be used as entry certificates. For example, if a company prints a document with a computer and writes the word invoice on the letterhead, it is already a formal invoice, but it must have the company seal or signature and seal.
In the eyes of the industry, a formal and valid Hong Kong receipt needs to be stamped with a signature stamp and signed by the directors, especially the terms of the contract. General shopping receipts are more like coupons. As long as there is no legal dispute involved, it doesn't matter whether it is stamped or not. However, as long as you feel it is necessary, you have every right to ask the store to stamp or sign the receipt and will not be rejected.