you can put a QR code on a metal sheet nailed to a post and call it a day. And at least where I live the app option is also accompanied by an SMS number to text

you can put a QR code on a metal sheet nailed to a post and call it a day. And at least where I live the app option is also accompanied by an SMS number to text payments to. An actual payment terminal requires electricity, a network connection and maintenance. And it has to be rugged to deal with the outdoors environment. If it takes cash, it also needs to be fairly rugged to prevent people from making off with the cash, and the cash receiving bits need a fair bit of maintenance as well.