I remember reading a blog post by the guy who did the fire for Far Cry 2. He spent a year on it. He didn't even do any of the graphics. He spent an entire year just playing around with fire spreading algorithms. An entire man year, spent on making the effect of one weapon look cool. Absolute madness.
On your mention of Garbage Truck Simulator, Euro Truck Simulator 2 came out not too long ago. All you do is drive a truck, that's it. It's selling pretty well, and has a development team of about 10 guys.
Why don't people in the big games companies realize all they need to do to be successful is make small, focused, FUN games, that have development teams of 10 or so. The rise of the indie game genre pretty much proves that it is financially viable.