Build quality is less about how the interior seems cheap or not but about tolerances. A Camry can have cheap plastic everywhere, but if the connection points don't rattle, it's a "better" build quality. But the truth of it is that the majority of people don't notice the build quality. A cup holder is a cup holder, even if it slightly rattles or is slightly off center.

The main example is the panel gaps on Tesla body. They can be offset by a "large" amount compared to other car brands, but it doesn't harm anything and you have to look for it to be noticeable.

So do Tesla's have a bad build quality? Yes, if you define it by tolerances, but no if you define it by "Does it feel low quality". And the debate online is largely with people talking past each other with differing definitions of what build quality actually means.