Clothing companies do produce them every now and then, but they systematically don't sell well, as similar clothing without proper pockets looks tighter, slimmer, and gets preferred by the majority of shoppers.
I would caveat: The majority of shoppers who buy clothing regularly and are into fashion. Which it makes sense for fashion companies to prioritize. Practical women who make pockets a priority also don't replace clothes just because they're out of style, take fewer chances on new things, and buy less.