With the growth of professional infantry in the United States over the last three decades, there has been, not unexpectedly, a growth in companies that supply equipment for the troops. That is, gear that is demonstrably superior to what the troops were being issued by the government. This is not an entirely new phenomenon. American professional soldiers had long purchased superior gear from commercial firms. But after World War II, with a large peace time army and marine corps, better pay for the career soldiers, and a growing industry supplying new products for hunters, campers and police, it was only natural that many of the mail order catalogs for these firms should show up in the mailboxes of infantry NCOs and officers. 

When the army became all-volunteer in the early 1970s, the new recruits, over the next decade, began to assume the same professional attitudes as the career NCOs and officers that led them. It became common for the troops to buy the same commercial gear (better sleeping bags, rifle cleaning gear, cold weather gear, Etc.) as the career NCOs had long done. But the commercial companies began producing more and more stuff that was suitable for professional infantrymen. Part of this was due to the growing popularity of paramilitary SWAT teams in police departments. But part of it had to do with the growth of paint ball combat as a sport. There was also an explosive growth in camping and hiking, as well as continued popularity of hunting. All these leisure time activities required equipment that was also useful for infantry. The commercial firms noted this, and began designing and manufacturing gear especially for the military market. Some foreign firms got into the act. Companies in Israel and South Africa produced superior military gear, and sold it to an international market. 

A lot of the equipment troops were willing to buy with their own money was pretty mundane. Load bearing equipment (for carrying extra ammo, grenades, flashlights and whatnot) was popular, as were better backpacks, underwear and socks. Better boots were also popular. The army and marine unit commanders did not go along with all this non-standard stuff, and having their favorite gear banned was another of those uncertainties an infantryman had to worry about when he got a new commanding officer. The army organizations that designed and authorized the official gear also noted the competition, and the reaction of the troops. Eventually, the military bureaucrats decided to, for the most part, cooperate with the commercial firms rather than constantly be at war with the troops they were supposed to be serving. One reason for the change in attitude was the arrival of the Internet in the mid 1990s. This began putting all the troops in constant touch with each other, and forming a block of public opinion that bureaucrats did not want to tangle with. 

As a result of all this, combat troops today have better gear than ever before. But its no accident, and a lot of people and companies unwittingly played a part in making it happen.