I don't know the reason why.

https://lemmy.world/post/43411660

IF you’re actually curios, it was because we used to import them, and the importers would dye them red due to discoloration in how they were harvested. Domestic production ramped up in the US and since pistachios didn’t have to travel as far, and because modern harvesting was more mechanized. It was easier to wash, dry, roast and salt them in a shorter time period avoiding the discoloration that required the dye in the first place.

Wait, this is real? I thought this was a joke…

Like “Back in my day, bananas were bright purple, but that breed died out.”

I also figured this was just a “let’s screw with the youth”-type post. We used to eat pistachios all the time when I was a kid (I’m 35) and I don’t think I’ve ever seen a red one before today. They were always beige/greenish.
We over-60s remember when pistachios were red, airplane security was non-existent and everywhere smelled like cigarettes.
Hey, I’m not even 40 and I remember getting to check out the cockpit of a plane multiple times. And the brown glass ashtrays at McDonalds.