All the people here saying “well of course because they weren’t trained on AAVE”:
THAT’S THE WHOLE POINT
It’s the same reason facial recognition and voice recognition software have a difficult time with anyone who isn’t white or a speaker of perfect, uninflected standard english. The bias is created by the developers, conscious or not, because they only train it on what’s in their own bubble. If you don’t have diverse teams behind the development and training, you will create this bias, whether you want to or not. This is well known.