Atms Where There's No Charge To Withdraw Cash,

[sandyRoe]

Who pays for it?

There's one outside a local supermarket, would they be paying for it in order to attract customers?

[Old_Geezer]

Probably owned by the bank that will have an arrangement with other banks not to charge. 

[Bazile]

In the case of free-to-use cash machines, the card issuer pays a fee to the ATM operator for each transaction

[barry1010]

No. The ATM owner pays the supermarket 'rent' for the site.  The issuing bank pays the ATM owner every time the card is used.