Final assembly has the lowest level of automation in the plant and the highest number of variants. Every module that goes in is expensive, heavy and has to pass through an opening that was not designed for it.
Robots place cockpit, glass, roof module, drive unit, seats and wheels into a body that hangs in a carrier and never stops in exactly the same spot. The system measures the real position and the real free space before anything moves.
What gets inspected here is what the customer sees and what the warranty pays for. Gap and flush on every attachment part, adhesive beads before the glass covers them, plugs before water finds them, and the correct variant of every visible feature. On every vehicle, not on a sample.