Pro tip for #HCPP19 visitors: you can open a #LightningNetwork channel directly to the point-of-sale system's node. The ATMs offer an "open channel" button, where you can find the node address.
Also, if you were inclined to prove to Paralelní Polis that accepting zero-conf on-chain transactions is a bad idea, there's an Android app called "PayNoWay", which lets you test their system against double-spend attacks. Rumor has it that some people drink beer for free here.