It's mostly as a result of pre-bundling and commercial agreements. We've seen the gradual move away from AOSP to a situation where 'Google Play Services' becomes a closed-source dependency for almost every major Google App, together with their iron grip on device manufacturers to strong-arm its installation in exchange for access to their ecosystem.
At that point, Play Store is the default and most users wouldn't need/want/think about moving away from it.
But also.... ....just in case those naughty users did think about being unfaithful. There is a lot of ethically gray UX design that makes it harder for a third party App Store to gain as deep an integration into the OS, by raising the barrier.
For example, overly alarmist alerts relating to security / unknown sources. Your average techie might know what they're doing, but they're sufficiently scary for your mum to probably abandon her attempts to install that third party App Store and just use the default.
If you install a third-party store, every installation is met with scary warnings about installing from unknown sources and how unprotected you are.
It's hard to make a store work if your customers are bombarded with warnings about how dangerous you are.
But you better believe that change is significantly because of fear of antitrust regulation than Google doing the right thing.
Google generates revenue from YouTube by artificially hindering the YouTube app by preventing it from playing videos in the background or with the screen off unless the user pays for a monthly subscription.
NewPipe removes that artificial barrier.
The Google search term "how do I play YouTube videos in the background" yields over 2 billion results[1]. There is an incredible amount of demand for this feature alone.
[1] https://www.google.com/search?q=how+do+i+play+youtube+in+the...
The only way I'd see alt stores being successful is if first-party stores were banned. This is pretty much what has happened with Android in China, but the UX is a mess. Users have to install a half-dozen stores, with each store taking up a pretty significant chunk of system storage and resources and with each store managing updates independently (which often creates weird conflicts when the different stores interact with each other). And for all that trouble, it's not even as if these stores charge developers any less than the App Store and Play Store do. Why would I as a consumer voluntarily sign up for this?
The value in the Play Store and App Store is that it is a single, centralized repository where users know they can find and manage all of their software. This significantly reduces the cognitive load associated with software installation.
But if it were actually possible to build a competing store, you would see companies offering features, innovations, and value that you will never see from Google or on Google Play. That's the free market.
I know I would install a store that was actually curated (not like what Apple and Google claim) with apps that have no malware, maybe no ads, etc. There are a lot of potential business opportunities in this space that cannot possible succeed today with the current anti-competitive practices of Apple and Google.
For example F-Droid is actually very big particularly with users trying to get rid of google services on their phones. But it's a marketplace for opensource apps and services, which most commercial apps are not.
e.g. Quasseldroid is distributed that way. The result is an awesome store UI, instantly deployed updates, and independence from the Play Store.
The only disadvantage is that, because it's not preinstalled, no one knows about it.
Instead I get a crappy app with very outdated repos. That's not good enough.
If the user tries to install an app on their own, they're shown scary warnings and must adjust arcane settings, but if they use Google's Play Store, no scary warnings are shown and no settings need to be adjusted. They're told they're "protected" by Play Protect, but aren't shown scary warnings about the fact that the Play Store is the main distribution method for malware on Android[1] when they go to install apps with it.
The Play Store isn't alone in being a vector for malware, as Apple's App Store is responsible for nearly half of a billion malware installs of just XcodeGhost alone[2]. This is why the mobile app distribution market needs healthy competition.
[1] https://www.zdnet.com/article/play-store-identified-as-main-...
[2] https://www.vice.com/en/article/n7bbmz/the-fortnite-trial-is...
For paid apps, Google could always cut less than you if they feel threatened.
And Google controls the Android OS development.
BTW, there are tons of Android app markets in China. No monopoly there.
Otherwise, Google threatens manufacturers out of the Android ecosystem, and will not allow them to install Gmail, Google, etc apps.
So, there is no competition at all. Google is a monopoly.
An app store is not a product, it is a feature.
Now on top of that, you have these burdens that make it practically impossible to compete with Google, even if you have the funding, talent, and a better product:
* You need to train every potential customer on how to find and enable the "allow unknown sources" option on their phone (which is different on every phone, and constantly changes place between OS updates)
* Convince them to ignore the many scary warnings from Google about malware and security and all that stuff when they try to do so
* Teach them how to download and install an APK from your website (and maybe how to deal with the Play Protect pop-up that insinuates your app is possibly malware)
And if you manage to do that with enough customers to build a sustainable business (unlikely), you'll still be at a competitive disadvantage on their phone because your store can't install updates automatically, so you need to send users annoying notifications to install updates manually.
You're also at risk of being targeted by Google's competition ~~hit-squad~~ I mean Project Zero, which, if you get in their sights, they will analyze your store around the clock until they find a vulnerability, and then irresponsibly disclose it in order to scare customers away[1]
Plus there's Play Protect, which (at least last time I checked) you can never really get rid of. When you install an app, it will ask you if you want Play Protect to send it to Google for analysis. If you decline, it will just ask you again later.
And if you accept, Google's notoriously unreliable bots could decide that your app is malware, and then block it from being installed on any device. Good luck getting a decision like that resolved.
[1]: https://arstechnica.com/gadgets/2018/08/fortnites-android-vu...