Pockets in women's clothing are smaller, fewer, frequently decorative and often absent entirely. This is consistent enough across brands and price points to be a property of the category rather than a series of individual decisions.
The historical account
Which is well documented and explains the origin if not the persistence.
Pockets were originally separate items tied around the waist and worn under clothing, accessed through slits, by everybody.
Men's clothing incorporated sewn-in pockets earlier and more comprehensively.
Women's fashion moved toward narrow silhouettes where a filled pocket disrupted the line, and the detachable pocket was displaced by the handbag.
Which established a division that has persisted through many subsequent changes in silhouette, including periods when the silhouette would have accommodated pockets perfectly well.
The commercial explanation
The part that explains persistence rather than origin.
Pockets cost money. They require additional fabric, additional pattern pieces, additional construction time, and they add points of failure.
On a garment produced to a tight cost, removing them is an available saving that does not affect the appearance on a hanger.
And the handbag is a substantial and profitable category, which creates an interest in the accessory remaining necessary. That is frequently asserted as a deliberate strategy and is more plausibly an alignment of interests than a conspiracy.
The fit explanation
The one designers actually give, and it is not unreasonable.
Women's garments are more frequently cut close to the body, and a pocket adds bulk exactly where the fit is tightest.
A pocket with anything in it disrupts the line, and a pocket without anything in it still adds a layer of fabric.
Which is a genuine design constraint for close-fitting garments and does not explain the absence of pockets in loose ones, where the constraint does not apply.
The measurements
Worth citing because the disparity has been quantified rather than merely observed.
Analyses comparing pockets in men's and women's jeans across brands have found women's front pockets substantially shorter and narrower, to the extent that many cannot hold a phone or a hand comfortably.
A substantial proportion were found to be too small to hold common everyday objects.
And false pockets — stitching indicating a pocket that does not open — are common in women's garments and rare in men's.
Why it matters beyond convenience
The argument that is more than an irritation.
Carrying a bag occupies a hand permanently, which is a practical constraint on movement.
It creates a security consideration that pockets do not, since a bag can be set down and forgotten or taken.
And it is a cost, since the function that is free in one category requires a purchase in the other.
None of those is catastrophic and all of them are a real asymmetry in how clothing serves its wearers.
What has been changing
Some genuine movement, driven by demand.
Pockets have become a stated selling point on some garments, advertised explicitly, which indicates that brands have recognised the demand.
Workwear and outdoor categories have generally not had the problem, since function dominates and the same pockets are specified for everybody.
And smaller makers frequently include them, since the cost saving matters less at lower volumes and the differentiation is worth more.
What actually helps when buying
Check whether pockets open, which sounds absurd and is necessary.
Put your hand in them, which reveals depth immediately in a way that looking does not.
Consider that pockets can be added by an alterations tailor to many garments, at modest cost, which is rarely suggested and is entirely possible for side seam pockets.
And note which brands do it consistently, since it is a design philosophy rather than a per-garment decision and tends to be reliable.
The children's version
Worth noting because it demonstrates that the pattern is learned rather than functional.
Analyses of children's clothing have found the same disparity — pockets smaller or absent in garments marketed to girls, present and functional in those marketed to boys.
There is no fit or silhouette argument available at that age.
Which suggests the convention is transmitted through the design tradition rather than derived from any requirement, and that it is applied before anybody's body shape could justify it.
Adding them
The remedy that is more available than people think.
Side seam pockets can be added to most skirts, dresses and trousers by an alterations tailor, at modest cost, provided there is a side seam to work with.
Patch pockets can be added to almost anything, though they change the appearance visibly.
Deepening an existing shallow pocket is also straightforward where the garment construction allows.
None of this is commonly suggested and all of it is routine work for anybody who does alterations, which is worth asking about rather than assuming a garment is fixed as bought.
The bag as a consequence
Worth following through, since the two are connected.
A garment without usable pockets requires a bag, which means a purchase, a thing to carry, and a thing that can be lost or taken.
Which converts a construction saving by the manufacturer into an ongoing cost for the wearer.
That transfer is the clearest way to state what is actually happening, and it is why the complaint is more than a preference about design.