Yes, this does indeed happen but when you look at ticket prices at these games there isn't much to compare to other leagues around Europe. I was talking to someone about how much a ticket would cost to go to EPL game and he said something along the lines of over a hundred dollars, if you can even find a ticket. The tickets for MLS games are almost free which i suppose is fine until you consider that there are costs associated with maintaining a stadium, security, and the cleanup and what not, so when Chicago Fire is selling tickets for $10 they likely lose money unless the attendee buys a bunch of food and drink or some merch!