Illegal monopolies and anti-competitive behavior[0] have that effect. Such arrangements may produce the best widget available but probably not the best widget possible. More to the point, they definitely don't produce the best possible widget for the best price.

That said, I wish Levi's still used YKK or something better than whatever no-name garbage zipper they use now in the cut I've worn for years.

[0]https://www.reuters.com/article/idUSL1926941520070919

I've had more than one YKK zipper fail on very expensive technical jackets. Not sure if I was just unlucky, or your statement is wrong.

Opti also make some pretty good zippers. There are certainly very few good manufacturers in this space though.