It's called cash people. Cash....C...A...S...H. You know, as in physical money.
Minimum spend? What's the smallest denomination in your local currency? Done.
Small purchases made via electronic payments are stupid.
It's also hard to overdraft and get slapped with the fees when using cash as well. What, no cash in your pocket? Yeah, you're out of money. Self limiting.
Oh, and WTF of buying coffee all the time....mumble, mumble, mumble....latte factor......mumble, mumble, mumble.