A reservation is normally made for sometime in the (near) future. In some cases this is immediately followed by a (down) payment. Various payment providers are suitable for this. But then comes the moment to which the reservation relates. This is often on location. Think of an hour of bowling, a restaurant, a game of padel or a meeting. In many cases there is some form of catering available. How nice is it if you can pay for the reservation immediately with the additional items ordered. Then a POS integration comes in handy.