Whoever is running it could set up alerts to just go empty it whenever amount taken reaches a certain value.
In terms of legality, I think *technically* you need a money transmitter license in the UK - although at the same time they say #Bitcoin isn’t money - so not sure. I think however, for small amounts to friends and family that’s ok.
Technically you could run these in stealth mode as no KYC to run a node that dishes out the Sats with the operator unknown?! ;-)
Stealth (or even not) ATMs cropping up on BTC Maps would be pretty cool :-)