I'm guessing that all these schemes timeshare one resource - people - who then diversify their enterprises by wearing two hats.

Sort of how a convenience store has a storefront, then keeps leveraging it by adding things like moneygrams and lottery ticket sales and utility bill payments and so on...

I also think there must be crops that benefit from shading. Either the crops grow well in indirect sunlight, or the area is too hot/sunny for the direct sunlight crops.