To me it seems entirely dependant on where you are riding. I used to live in between the city and suburbia. When anywhere near the city I agree it was not safe to ride on the sidewalk, Partially because some are super narrow, partially because even the wider sidewalks are usually covered in foot traffic. The only exception was when I was transitioning to the mups. But in the suburbs, I am not putting myself alongside traffic going 50 at a minimum. I take the bike lanes when I can, but it is a total crapshoot wether or not a given neighborhood will have any to speak of. I make an effort to stick to mups and side streets when possible, but any major roads I usually end up on the sidewalk until I get to the next mup entrance/sidestreet.