Short story long: My recent experience was interesting with ATM's at Dublin Airport. At larger airports like Frankfurt, Schipol, Heathrow or CDG there are multiple ATM's as you walk through the terminal. I've always advised getting cash at one of the ATM's. Bank owned ATM's in Europe don't charge you for the transaction.
Your bank will charge you. In the U.S. the big banks charge $5 plus 3 percent on every transaction. My bank, and lots of smaller banks and credit unions, charges a flat one percent of the transaction (100 euro would cost me one euro rather than, roughly, eight with the big banks).
Before ATM's, debit cards and improved international transactions, people carried cash (or traveler's checks) and converted to local currency at exchange booths. Both are expensive options that are virtually outdated by the convenience and cost savings of bank-owned ATM's. The exchange companies are clever enough to have created ATM looking exchange booths. I'd guess most people never notice they aren't bank owned. They come with the same expensive transaction fees that made most people avoid exchange booths in the first place.
In Dublin, the first ATM's you will notice in Terminal 2 are Euronet, which is an exchange - not a bank owned ATM. I looked at them and decided I'd look for a bank owned ATM. It was somewhat of a search but I found a Bank of Ireland downstairs. For whatever reason, I stuck my card in and it said my card didn't qualify for 24/7 cash. I found another Bank of Ireland in Terminal 1 and it worked fine. Aside: I had several similar issues with Bank of Ireland, some worked, some didn't, which caused me to brand them the cash nazi (a play on Seinfeld's soup nazi, "NO SOUP FOR YOU!"). I'd guess when the machine senses it's low on cash, it stops giving cash to non-customers.
I've been seeing more of these Euronet machines in airports. In Orly (Paris) there's a big ATM sign and under it is an exchange machine (not an ATM). Surprisingly, I saw a lot of Euronet machines in downtown Dublin as well. It (literally) pays to pay attention to whose machine you are using. Sometimes you need to pass one up and find the bank owned machine.