This overlooks that the Rubin telescope has a relatively wide field of view and a thirty second exposure time, so LEO satellites do routinely appear in images.

This overlooks that the Rubin telescope has a relatively wide field of view and a thirty second exposure time, so LEO satellites do routinely appear in images. The size of the object isn't so important as its relative brightness, so while a car on the surface of the Earth is hard to locate from 400km above, a sunlit car 400km up in the night sky is visible to the naked eye.