Android is pretty standardized these days, and even a fairly cheap Android phone will probably do most smartphone things (make calls, send texts, watch YouTube, etc.) reasonably well, but a corner that seems to be cut in cheaper phones is almost always the camera, and that kind of makes sense.
If you're buying your phone online, you can look at the more-or-less objective specs of the phone like how much RAM it has, or how fast the CPU is, but you can't really tell how the photos will look [1], and as such it's easy to put a cheaper sensor or lens in there, especially in the cheaper phones which (I think) have lower margins.
[1] Even if the listing has sample pictures, you don't know how representative they are of the actual experience; they could just have taken the sample photos with ideal lighting, with a tripod, in a controlled studio, for example.