In a lot of places, it's actually illegal to ride a bike on the sidewalk. Between risking a ticket, dodging pedestrians, and a bumpy fucking surface that hurts your ass after a while, riding in the street is often the better option. And if I hold up traffic, well, they shouldn't have gotten rid of the bike lanes in favor of in-the-street parking.
FYI, I'm from Detroit, where the city (and the suburbs) seem to be actively designed to be hostile to anyone not in a car. You can't pass through fucking Bloomfield without actually riding in the street on Woodward, and god forbid you're trying to go somewhere in the city, even the buses won't stop in city limits, because fuck you for being poor. Fuck Oakland county for slashing 13 million from bus funding, and fuck GM for buying the rail line and tearing it up so you have to buy their shitty cars to get anywhere. And fuck the AG for only fining them $50,000 for it.