In Peru I could use BCP ATMs for free, I'm from the UK using Mastercard. I know some other nationalities were maybe charged at BCP but able to use a different bank ATMs instead. Like Scotiabank would charge me but not some others I met.
I just withdraw money from the cash machines. I have a Wise card, so i get two free withdrawls of cash per month up to a certain amount, and then after the charge for withdrawing is really low I've found that the charges are less than what I've lost in the exchange rate when I've exchange USD for local currency. In Peru there are Cash machines you can withdraw money from that don't charge. In Chile I've yet to find one that doesn't charge. In Chile though as a foreign tourist there is a 20% fee on accommodation unless you pay with a foreign credit card or America dollars. But be aware that places wont accept American dollars if the notes are riped, crumpled or have any kind of ink or stain on them.