E.g. if it can only do file accesses outside of it's own settings folder after prompting me, I know that it has way less abilities to screw up my system.
I don't think that can replace a package manager for "complex" or "infrastructure" software, but for other things it could open the selection up. Many people already run sandboxed applications, in sandboxes called "Firefox" or "Chrome".
Lately I've found myself checking if something is available on F-droid before installing from Google Play. Sometimes it is!
If something is on F-droid, I'm less worried about it being scammy spyware disguised as useful software.
Downloading a binary blob in the first place was the real issue. However, the voice recognition module wasn't actually used unless you opted into the "Ok Google" hotword feature.
Getting back on topic, Android handles similar problems in a different way, via the permission system (esp. the improvements in Android 6.0+).
So says someone, but you don't know what else the binary blob (which can be "updated" at the will of Google, without asking anything to the user) does for sure, do you? If you're content with that explanation, you're essentially taking their word for it with blind trust. For example, will it push a new binary and/or suddenly start listening to you or send certain files from your computer if someone three-letter government agency tells Google to do so? Would you bet your life on it?
Trust in software may not be that serious for you, but there are people out there whose lives depend on it.
The issue here is twofold, and in terms of security, it being a binary blob is the lesser one: 1) this is a binary blob which hasn't been vetted by the eyeballs of FOSS world 2) Google circumvents the package manager (along with package reviewers and FOSS community) and secretly and freely installs (and updates) a binary blob on your system, which is essentially a closed-source backdoor singularly controlled by a US company.
A program that silently pushes programs on users' systems (and silently executes them!) at the pleasure of a company never had any place in Debian or any distro with similar principles. It wouldn't matter if they pushed the source code and compiled it on your system (in fact, some rootkits work just like that).
> Getting back on topic, Android handles similar problems in a different way, via the permission system (esp. the improvements in Android 6.0+).
You're talking about a totally different problem/class of permissions here though (accessing network/video/audio/filesystem etc vs ability to install packages as a non-root user).
Of course you could say in a large codebase like chromium, bad things can be hidden. But at least there's a better chance such things are found, and it's more risky to put it there in plain sight.
In a perfect world, all software would have reproducible builds and there would be no issue with trusting that binaries contained no hidden functionality not in the source, as there'd be third parties to rebuild and compare the result against the published binaries. We're a ways away from that.
You can't use it to deny specific permissions, only groups of them. If an all wants to write something your contacts, you also have to allow it to read them. This even though the core permissions system allows that level of granularity.
also, network access is deemed safe (by Google) and is thus in a group of permissions the user has no control over.
High-standards imposed by distros (see for example: https://www.debian.org/doc/debian-policy/) and tedious work of packagers has been a very important part of the free software ecosystem, and kept GNU/Linux snoopware-, malware- and virus-free and trustable [1]. They are far from "unneeded middleman".
Here's a very recent example of this system at work: Chromium sneaks a binary blob which secretly listens to your microphone and sends data to Google: https://lwn.net/Articles/648392/
This is just one instance, there has been many many examples of this.
There are just so many, let me say, shady, "apps" out there, so I don't install anything from Google Play Store on my smartphone. On my desktop/laptop however, I feel safe installing whatever I need from the official repositories. I personally don't want to use a distro to which "app" developers from Android ecosystem can freely push their programs (and updates to them).
> Applications being files/folders that can be installed/uninstalled with cp/rm seems way more unixy to me.
But that's essentially what a package manager does for you, although it takes away your freedom to screw up in the process. In GNU/Linux, it essentially 1) protects you from screwing up your system accidentally 2) allows you trust system-wide binaries (assuming that your distro is trustable).
App Stores are also package managers, so I'm not sure what you're trying to point out here.
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[1] I'm excluding Ubuntu here. Ubuntu comes with spyware, spies on you by default and monetizes the privacy and trust of its users [2]. I don't trust it, I don't use it, and I recommend against it.
[2] http://www.gnu.org/philosophy/ubuntu-spyware.en.html