This is mostly a framing war. Calling it "sideloading" makes it sound risky or unusual, but if we called it "installing software on your own device", Apple's and Google's restrictions would seem absurd - like telling homeowners what kind of light bulbs they're allowed to use.

Or what kind of store you can drive to.

Imagine if your car was locked to certain manufacturer-permitted destinations.

That's what our smartphones have done.