While not your typical Credit Union, most governmental unions, such as SECU, LGFCU, etc, do not have any transaction fees no matter the ATM used. Now if that ATM, itself, charges a fee for non-member use then you have to pay, but your credit union doesn't.
For instance, I am able to use Bank of America ATM that's right around the corner from my house to withdraw money from my SECU account, for no additional charge.
But BOA charges you a fee, right?
There is one credit union atm between my house and my job, but its just a lot easier to use Wells.
Fwiw, I have an account with a credit union and with the bank.
Credit Union had some great auto loan rates, so we got a car loan there and opened a savings account with them at the same time. Its easier for me to save money with them because they are inconvenient.