There is a section on one of my commuting routes where the choice is between entering (from the east side at a stop sign) a northbound 5 lane (2 x 2 + turn), cross two lanes of northbound rush hour 30 mph traffic to get to the west turn lane in less than a half a block, or ride 1/4 block in parking lot and 1/4 block on a sidewalk to get to a pedestrian crossing, which puts the crosser on the south side of an east west 5 lane 2x2 plus turn, on a sidewalk. I opt for the sidewalk for my own safety and well being, not to mention the psycho cager, rush hour, nutbags with sun in their eyes, not paying the least bit of attention to the bike sitting in the middle of this intersection. Once across the intersection and to the next curb cutout, its possible to cross to the westbound side of the street and continue on the road. There is really no other choice as the next stoplight to the south of this intersection is an interstate highway on/off ramp and the next light to the north is the busiest street in the state.

As has already been stated, its usually best to mind your own business, especially when you have no clue why someone may be utilizing the sidewalk.