Most sidewalks aren't appropriate for cycling. The exceptions I was describing are mostly found in big commercial developments, target, walmart, etc. Around me they tend to build wide sidewalks, well separated from the busy road. Here's an example:
https://www.google.com/maps/@38.9146941,-92.3196647,117m/dat...
But most sidewalks aren't like that they are crossed regularly with driveways and end at a road every block. Every driveway is dangerous because drivers just don't look for people moving at bike speeds(2-3x faster than a pedestrian) on sidewalks. I personally know two people hit while cycling on a sidewalk because somebody pulled into a driveway and didn't see them.
Imagine you're a cyclist, on the sidewalk, trying to cross a four-way stop. If you cross at the sidewalk, you're at extreme danger of being hit by a car making a right turn. This is called a right-hook.
The road infrastructure in the US was built without consideration for bikes and so it's really annoying to many drivers when cyclists use roads but that doesn't mean the right place for cyclists is on the sidewalk.