The actual answer to your question is that the Atari 2600's fundamental limitation is sprites per scanline, not per screen. It can draw lots of objects by reus

The actual answer to your question is that the Atari 2600's fundamental limitation is sprites per scanline, not per screen. It can draw lots of objects by reusing sprites across many scanlines, but can't draw many objects that need to move independently in vertical space. So you can draw the "3D" racetracks by reusing two sprites all the way down the screen for the road boundaries, but you can't draw three Pac-man ghosts on the same scanline so you have to flicker between them on alternate frames.