I'm not sure what it is about currency exchanges that seem quintessentially "Chicago" to me. Maybe because I never saw one until I moved here. Every service they offer can be found somewhere else (and more cheaply) but they conveniently bring everything right to the corner for a modest fee. The first time I renewed my city sticker at a currency exchange I was surprised to have them fill out the forms right in front of me. What luxury! All I had to do was sign.
Of course if you don't have a bank account and depend on the currency exchanges to cash your paycheck and pay your bills its much less of an adventure. Those percentages add up. In my neighborhood a lot of people don't have a choice. It's a very profitable business, without much local regulation.
