A relatively small number of caches are by and for premium members. It doesn't mean they are necessarily better; some people don't like to have their caches found with the free app, or have other reasons. I looked at the map from one of your found caches, and there aren't that many near you. I wouldn't worry about it.
Thanks for checking! There are a ton of caches near me, so I probably won't upgrade to premium for awhile. And I'm also having troubles finding caches lol. I think I need a better "sense".