system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are there not billions of fruit flies all over the grocery store?

I bring home a couple peppers and an onion, now a couple weeks later I have tons of fruit flies in my house.  What does the grocery store do to keep them from infesting?
gpt
Fruit flies generally go after rotten fruit, not regular fruit, because then they can get through its peel or rind to lay and hatch eggs on the nutritious sugary part. The rents and tear in rotting fruit allow the insides to gives off gasses and esters that strongly attract them. Then their eggs hatch and they breed very quickly, taking only a few days to mature into flies that buzz around the area.

Supermarkets do their best to remove damaged or rotten fruit as quickly as possible, and they usually have a very high turnover of produce so nothing sits around and goes bad like the apple that fell behind the bowl out of ~~site~~ (Edit: sight *sheesh!*) or the pepper that was mishandled and cracked open on the wall-facing side of the counter. 

Traffic is also very high unlike areas of our house. The minute the produce section guy spots a few fruit flies buzzing around something, they get rid of it to avoid disgusting their customers. The produce department is not left unattended for the hot part of a full day, unlike our kitchens or larders when we're at work.