IMHO you have it backwards. The women that control clothing decisions are a small minority of all women. I bet if you polled women you’d find a majority that would favor larger pockets.
The apparel/garment industry is highly fragmented with a low barrier-of-entry. It's not as "top-down" as your sentence seems to be implying. There are plenty of how-tos on the web explaining how to turn your clothing designs into products using contract manufacturers in China etc. That's why amateur Youtube influencers with no experience in the garment industry can "launch" their own clothing lines.
It seems that if "women's pants with bigger pockets" was desired by enough potential buyers to be profitable, some entrepreneurs would already have taken advantage of that arbitrage opportunity and become rich.
I agree with the sibling comment[1] that women may prefer bigger pockets if that one characteristic was isolated -- but they also prioritize other aspects such as the "look" the pants that end up forcing smaller pockets. Women's clothing is often a prime example of form-over-function (as a deliberate tradeoff) rather than function-over-form.
If we conducted a poll of 50 women, we might well find most of them say they want pants with bigger pockets. If you start a big-pocket line of womans clothing, you'll probably sell a lot less than someone who tries alternate tactics. Or make a fortune, what do I know. But if anyone believes there is a fortune to be made they can go try that remarkably easily and yet small pockets persist.
Calling them liars is a bit much in this scenario. I would blame the poll more than the person answering the poll. If I ask you: do you want a Porsche? You might say yes, but if i say: i can give you a Porsche for a million. You will probably say no.
They should probably ask a more nuanced question around what kind of trade-offs people would be willing to make for those bigger pockets.