Accelerometer on Moto G is bad from factory?
From what I can see in the video, the fluctuations are within about 1° in the first app, and 0.5° in the second. That's not exactly "random numbers in a wide range".

Accuracy within 1° is acceptable for most intended use cases: Mobile games, screen orientation, gestures, etc. It's quite possible that Motorola decided to use a cheaper sensor since the phone itself is intended to be a very low-cost device.

I wouldn't say that it's defective. Possibly subpar, but not defective.