The other answers: "Of course not, someone would haved picked it up already if it were"
Some times low hanging fruit is so low hanging that people don't bother to look for it as it's "obvious" someone else would had picked it already.
“I’ll pay you $100 if you eat that dog shit” says one
The other economist, being a rational actor, naturally eats the dog shit. He is given the $100.
But then he sees another dog shit. “Well, I’ll pay you $100 to eat that one!”
A second shit is consumed, producing $200 of GDP. The economists are overjoyed at their productivity and earnings.
Or you can see it as a very basic representation of money flowing in the opposite way of services and goods in the economy, you can even measure the speed of money with the amount of shit they make each other eat in an afternoon.