The most effective way Google uses to keep free software out of the Play store is the search function and description rules.
You can put free, user-friendly software into the Play store. The Play store shows whether software contains ads or in-app purchases. But the Play store doesn't let you search by those criteria, and IIRC developers used to be prohibited from clearly advertising the main distinguishing quality of their software in the title (couldn't find the rule in the policies anymore so this may have changed).
Likewise, users can't search or filter for app size, which not only affects how much space the app eats on your phone but is also a great proxy for how much crap is bundled inside it.
So in effect, the good apps will be impossible to find amid the sea of SEO-optimized and/or paid placements of ads that can afford to do that because they are full of ads.
Oddly enough, I try to search for paid software because if I buy a game, I want to be able to complete it. Not like pay $5/month to access half the game, and another $50 to get to the final 20%, and another $100 to get to the final 5%.
It's not letting me do that either. Google Play Games (the separate app) has such a filter but it's seemingly random.
People don't shop at Amazon for the amazing UI around buying stuff. It's absolutely ludicrously atrocious for a trillion dollar company. But the focus is getting you to buy the items that make them the most money, not the item you want.
You can put free, user-friendly software into the Play store. The Play store shows whether software contains ads or in-app purchases. But the Play store doesn't let you search by those criteria, and IIRC developers used to be prohibited from clearly advertising the main distinguishing quality of their software in the title (couldn't find the rule in the policies anymore so this may have changed).
Likewise, users can't search or filter for app size, which not only affects how much space the app eats on your phone but is also a great proxy for how much crap is bundled inside it.
So in effect, the good apps will be impossible to find amid the sea of SEO-optimized and/or paid placements of ads that can afford to do that because they are full of ads.