Yes exactly, there's plenty of space for a decent sensor and lens. On top of that we're talking about a wide-angle lens, which are generally flatter. Two things add thickness and complexity to camera lenses - telephoto and autofocus. Phones only recently started getting thick bumps for the rear camera when telephoto lenses became more popular. My phone has a sizeable bump for the telephoto camera but the ultra-wide angle one is outside of that bump.