Comment by Zak

I can understand why root is not enabled by default. Anybody who had to fix Windows PCs owned by average consumers a decade or so ago probably does too. The situation on Nexus and Pixel devices was about right: it requires the use of the command line (or third-party software), but doesn't try to resist. At least, it didn't until the introduced Safetynet so that apps can resist running on rooted devices.

I think the motivation for things like Safetynet is that general-purpose computers aren't good for business. If the user has full control, they might block ads, pirate content, or use content they legitimately paid for in a way a service provider wants to charge extra for.