Oct 27 2020
Apple, Google, Samsung, LG and many other device makers or mobile wireless providers pre-install their own and or third party apps on devices that some users do not want and disable the option to uninstall them.
Here is some more information on this including privacy and higher resource usage concerns, why they do it plus easy options to temporary disable preinstalled apps on at least Android. You can still enable again if you want to use them
Also learn about a method available on at least Android to bypass the restrictions and permanently uninstall these apps if you do not want to use them or to have a closer look at what they are doing in the background with location services, camera, mic etc…
Many people think it should be illegal to disallow the disabling or uninstalling of pre-installed packages. Anti-trust lawsuits in the past forced Microsoft to stop doing this with Internet Explorer and to release some hidden API’s that gave them unfair competitive advantage. More recently there have been lawsuits against Google, Apple, Facebook and other digital giants especially by the EU which has a better trend of trying to protect its citizens privacy and from wrong doings than many countries.
Adware is bad enough, but Facebook is seen by many as the most insidious kind of adware out there and this leads to concerns with these devices before the users even get their hands on them.
On at least some Android devices the Facebook and Facebook Services Apps are pre-installed, with default permissions and possibly running which can reduce battery time and has led to privacy concerns even if not logging in with a Facebook account. There is others like Facebook App Manager, Facebook App Installer and Messenger that maybe pre-installed.
If you prefer you can go to Settings > Apps > and search for the App, then Force stop and Disable. If you restart your device or update the App in the App store it will restart them.
Some people have still reported reduced standby time / higher battery usage after only disabling the Facebook App and not Facebook Services as well.
Uninstalling some built-in apps is disabled on some devices. On some of these you can’t even disable these built-in apps. You may have to disable or uninstall via Developer Mode and Developer tools. For Android you can use the ADB CLI tool which is part of the Android SDK. Anyone who lacks technical knowledge about this can learn some of it here along with how to check the logs for what apps are using location services etc…
Some ask what is the benefit to the device makers. Well they are often paid if they preinstall or build-in the apps.
What does Facebook gain from having these pre-installed? There have been responses like
“IP, Mac Address or Device UID targeted ads. Microphone spying to further develop a profile on users, cross reference names with accounts to find out who users are to assign real name, work address, school address, home address, political views, where you shop, eat, buy groceries, pretty much anything they could get even if you dont have an account, just slightly more resource intensive. And Facebook has those resources.
All this just to show you some ads… And the scary thing is: it works better than people think.”
Facebook has already been found to keep shadow profiles of non Facebook users via contact uploading and associations etc…
Facebook has also sold or leaked access to millions of users data to third parties like Cambridge Analytics and others which used this to create targeted and manipulative adds that have affected public discourse of many important issues, influenced politics, elections and referendums etc …
Related
Apple blocked Facebook and some other third parties from running their internal iOS apps after misusing Apple Enterprises tools.
Whats Up 
What exactly do Facebook Services, App Manager and App Installer do and will you still get notifications and be able to check in on Facebook if disabling?