It all comes down to the fact that women in general don't see small/absent pockets as much of a factor when buying pants, while men typically do. Those pockets cost money to put in and in the razor thin margin clothing industry that means the pockets are going to be missing or tiny.

Tbf though, it's quite possible at this point that there are so few women's pants with pockets that even those who do see it as a deal-breaker are unable to express their preference with their wallets. I also suspect those that don't value pockets would change their minds the moment they actually got pants with real pockets too.

I don't think this is going to change until enough women band together and start boycotting brands with tiny/absent pockets and start championing brands that do offer proper pockets. This kind of strategy does work btw, possibly a little too well. It certainly worked in make-up industry where up until recently they basically didn't offer shades for non-white people and now overnight all of them are viciously competing on who offers the most shades (in some cases hundreds). This issue may not have the same importance and power as racial equality does, but it's proof enough that if you kick up enough stink the market will respond. I wouldn't be surprised if women's pockets dwarfed mens if this ever happened.