The 405 Freeway underpass along Venice Boulevard has become a flashpoint in the escalating homelessness crisis plaguing Southern California. The road is a border between worlds. On the north side of the famed street is Los Angeles -- and a sidewalk packed with sun-bleached tents, dirty sleeping bags, bikes in various states of disrepair and even a few surfboards belonging to residents of the underpass’ homeless population. On the south side is Culver City, a storied moviemaking hub and a peaceful suburban oasis. On a recent weekday morning, Culver City’s side was noticeably bereft of any sign of the homeless...