Why do we eat unripened chili peppers?
You can get red jalapeños at some markets, but you're right, most places sell them when they're still green.

They sell them for the same reasons they sell green bell peppers, which includes:


some people prefer the milder, grassier notes (or just don't know better)
they're cheaper to produce (don't have to wait for them to ripen, reducing water use)
they store and ship better (as they're not ripe yet).
it lowers the risk of losing the harvest (due to weather, blight, etc. from waiting 'til they're fully ripe)
it reduces the number of field hands needed (as they're not trying to pick all peppers at the peak of ripeness)
if frees up the field for another planting.


In the case of hot peppers, it's more complex than the simple colored bell peppers -- the ripe peppers are often further processed (smoked or dried) and then sold under a different name:


chipotle == smoked &amp; dried jalapeño
ancho == dried poblano
colorado == ripe anaheim