FAQ for
The Hitcher (1986) More at IMDbPro »

She had already met Jim earlier in the movie when he stopped in at the restaurant where she worked to call the police. When he told her on the bus that he did not kill the police officers, she at least partially believed him. When it became clear that the police officers who came to the bus to arrest him were going to kill him on the spot, she stepped in to rescue him.

Most likely , John Ryder is a psychopath ,a lonely man who is tired of life ,but cannot commit suicide for reasons unknown. He ultimately persuits Jim so that he kills him. In the book ,John Ryder has no criminal record ,no date of birth ,no driving license and no social security number,it is presumed that he is an expert at psychology. In the novel ,after Ryder's death ,John actually influences Jim Halsey to start hitching himself ,however the exact details of Jim going on a rampage is unknown. There is an alternative version, that claims that John Ryder doesn't exist: is just the other side of Jim Halsey (like the mother in "Psycho").

This is a reference to Greek mythology, where the dead are often depicted as being buried with coins on their eyes and/or under their tongue. The coins are payment for Charon, the Ferryman who would carry the souls of the dead across the river Acheron to the underworld. The payment is known as an obolus, and bodies buried without it would wander the shores of Acheron for 100 years