What exactly does one complain about? If I complain to a movie theatre for all the money I've spent on tickets, they're just going to say "Um, okay..?"
This is a silly comparison. A movie theatre is an exchange of money for a one time service. Something most people understand. F2P gaming is something a lot more insidious. Like if the movie theatre was trying to nickle-and-dime you for a dollar or two throughout the day.
It's just one data point, but my mother-in-law, who's in her late 60's, plays a lot of free games. She did an audit of her spending last year and discovered she'd spent over $500 in Candy Crush (I think that was the game). She complained to them and they gave her a partial refund, though to my knowledge she continues to play the game. I would bet a lot of these players are less tech savvy older folks.