Re: All the power to them
Google provide the payment system, so removes that issue - and for small devs /companies, payment providers charge (depends on model, in many cases its a annual, monthly etc fee and a per transaction cut, if you only make a few sales then cost per transaction due to fixed monthly fees can be high, obviously if you sell a lot then most significant cost just becomes per transaction cut).
Google also provides play store with categories, search, suggestions , reviews of apps (if not on play store harder for people to see good OR bad reviews...).
For some games there is option of Google Play integration (not sure if that integration mandates goggle store download as I have not created games on android, just non game apps).
Google also does some basic checks for apps on store not having malware
So Google does not do nothing for its cut.
Disclosure: I have made fully free, very niche, apps for android & put on play store purely so easier for people to grab them (side load warnings scare some people) - , I got no cash, but nor did Google (but costs of hosting app on store, providing reviews etc was borne by Google so my apps would have been a net loss for Google)