By default the vehicle is there with your name on it (at least the ones I've been to here in SoCal), so the visual inspection is readily available. I just walk up to the delivery counter/stand and ask them to open the vehicle for me to fully inspect before signing any final docs. They'll open it, but won't give you the key card. They usually don't have a problem with it. That's what I did also this last time around on 9/11 when I attempted my first delivery, but then rejected the vehicle. Same when I went with my sister to pick up her MYLR back in June at a different Tesla delivery center.
Perhaps that delivery center for that other user was just being a pain. When I've gone, I'm seeing everyone looking through their vehicle with all doors opening and closing. Granted, I don't know if maybe some of them have already fully paid/signed.