The assumption is often that military gear is somehow special. In a few cases, things like sights and communications, it may be.

But you have to understand that mass produced USGI field gear ,like packs and uniforms, is seldom state of the art. It is designed to equip a large army of draftees. Ease of manufacturing and cost are often held higher than durability, comfort and effectiveness.

A good example of this is the venerable K-bar. They were designed to fill a need for a handy and functional, but expendable, utility/fighting knife that could be produced quickly, wouldn't use up strategic materials or require too much productive capacity. It is a good and effective knife but by design it was never supposed to be the finest knife out there. The military typically shoots for adequate and functional instead of 'best'.

The blade is common high-carbon steel that is vulnerable to both breaking and rusts in a few hours after a dunking in salt water. The leather rots in salt water and tropical jungles. The galvanized steel staples and stitching used to hold the sheath together rusts or rots.

Given all this vulnerability one has to wonder how any of them survived. Examples are still around because better than a million were produced and they were reissued frequently and in great numbers. In combat these knives were full expected to get lost, blown up, broken and, because there was little time for TLC, they deteriorated rapidly. Which is pretty common for all the field gear a combat unit had through Vietnam. The expectation is that at regular intervals essentially all their field gear would be disposed of, cleaned and patched if practical, and new issued.

Some of this dynamic has shifted as we moved away from a massive army of draftees toward a much smaller force of volunteers. Even the concept of USGI gear has slipped. Back through the 70s the vast majority of field gear was government issue through a government contracting and supply system issuing government approved designs. Now most units get money allocated that allows units to purchase gear directly from civilian suppliers. Most combat units purchase some portion of their field gear from civilian suppliers.

Many of the manufacturers of standard camping gear, and a considerable number of companies catering primarily to military users, cater to this lucrative market with a specialized product line. They fully understand that offering a backpack in camouflage and using military terminology allows you to double the price.

Typically servicemen get the best and worse of both the service supply system and whatever the civilian providers can supply. USGI field gear is usually pretty good. But seldom exceptionally good. It can be both functional and a bargain to equip a group with it. A good example of this is the venerable ALICE packs and frame. They work, are still used within the military, and they are inexpensive for what you get in capability. But they were never as comfortable, refined, or effective as they might have been. That is pretty much standard for USGI field gear.