Left turns on red from a two-way to a one-way are the same "difficulty" as a right turn on red, although the reasoning is less obvious. If a right turn is possible, the opposing side might have a green light and protected left turn, allowing the driver to get a permissive left turn (flashing yellow arrow). If the opposing side has a red light (which is the case if a right turn is impossible), or there is no opposing side, the driver has to yield only to vehicles from the right, and possibly the nearby crosswalk. In any case, the driver has to yield to only one stream of traffic (out of two possible streams), and zero or one crosswalk.