That doesn't really make sense. My bank's ATM has to be refilled with cash and they don't charge me. Likewise, I doubt the Walmart self-checkout is sorting bills and only dispensing $20's: they also have to be loaded with cash separately.
The only charges I encounter are from using my bank's card at another bank's ATM.
It probably depends on the type of account you have with the bank. I certainly don't pay ATM fees so long as I use my bank's own ATM but perhaps there are more bare-bones account types that do.
The only charges I encounter are from using my bank's card at another bank's ATM.