A hit-and-run driver seriously injured Jasmine Vega and Sean Kramer around 2 a.m. on the Southwest Side of Chicago as they walked across Kedzie Avenue at 43rd Street — shortly after an allegedly truculent Uber driver ejected them from his vehicle at 44th Street and Homan Avenue, around a mile from their destination in the 4100 block of South Albany Avenue.Proximate causation was the high hurdle for claims by Kramer and …