Originally Posted by AlwaysAisle

It was more for tax and other purpose from old days. It used to be that for tax purpose for the government, the receipt which cash register machines spit out was not good enough. As far as tax purpose is concerned the receipt had to be in the proper form with the stamp (Innkann, 印鑑 ). It used to be common that on business travel need to ask for Ryoshu-sho (領収書) to get reimbursement from the company. Receipts out of cash register machine was not good enough. The terminology is:

レシート:
Receipt cash register machine spit out

領収書:
Official document indicating cash transaction, in old days this was required for tax purpose.

Once I made a mistake at Haneda Airport checking in for a domestic flight. I had to change the flight and had to pay the fare difference. The check in agent asked me if I needed Ryoshu-sho (領収書), which my mistake I said yes. For me an itinerary printed along with boarding pass with fare amount was good enough. Agent went to back door and took few minutes to come back with the proper form with the transaction amount and Hannko (ハンコ) on the receipt.