"Everybody" uses Glocks to some degree or another.

As for business interests influencing design, production & adoption of military weapons, it's always been that way. Business complications and business profits drive weapons design and production.

The HP itself for example was hampered by the necessity to avoid patent infringement on the trigger mechanism and thus it's cobbled-together trigger & poor trigger pull by comparison to some other pistols. It's magazine was revolutionary at the time but suffered from a design flaw rectified by later designs. Cost to produce is no small issue if millions have to be made.

And...the Glock & subsequent designs are easier to maintain and possess extreme reliability and ultra-extreme round count life expectancy. And absolutely...cheaper to maintain.

I've owned piles of HP's over the years and they are excellent pistols, but the SA system is a disadvantage and they are basically obsolete at this point. Expensive to produce and in possession of a few functional disadvantages, the following generations of defensive pistols are just... "better".