This does not appear to be well known: kale really needs colder temperatures in order to taste best. It’s sweetest when it has been through a frost or two. Unfortunately that’s not always maximally profitable for Huge Giant Corporate farms and so your kale is grown in warmer temperatures and tends to be bitter.
On the plus side, it’s incredibly easy to grow yourself.
“I wanted to be outraged and lose sleep daily. I need to yell at my computer and throw things at my TV in order to feel alive”