Addressing a few posts upthread regarding people admitted to hospital with covid, claiming they have self-isolated and haven't left home.
OK....well, something or someone brought that virus into the home. There is no other way in he!! they picked up the disease without contact. It doesn't mysteriously sneak in through a crack in the door......moo!
Unfortunately, many people end up omitting details when they speak to doctors. This is very well known and the rate varies in relationship to the quality of the illness. People who smoke 3 packs a day tell their doctor they smoke 5 cigarettes. This is the kind of thing I study (and train students to study). It's amazing what a patient will tell someone who isn't their doctor - in a different setting.
Plus, we can observe people. The reason China put cameras outside of people's doors is that they were going in and out more than they admitted. Down the hall. To the trash (exuding virion all the way). No air circulation. It's winter. No air movement in communal hallways.
Then, in places like Long Island, people did stay home - except when they went out for religious services, funerals, etc. They were staying home so much more than they usually did, they considered it "quarantine."
Almost no one (except on Websleuths) is reporting perfect isolation - and even, it's just some of us.
One big factor is that people are afraid they will be denied or de-prioritized for healthcare, if they admit they went out of their apartments/houses. That they talked over the fence to a neighbor (let's just admit that 6 feet is a minimum distance - we know virion can travel further than that).
Until all of this is studied and documented in a non-medical, after-the-fact context (with total anonymity), I don't think we can assume large urban areas have most residents staying home *all the time.* Further, on every street, there are essential workers, who pass by and who infect their own families and housemates, so that's another subset.
IOW, people remain unpredictable. Some really try hard to conform and follow rules. Many cover up lack of compliance with fibs. Others flaunt the rules and lie.
And some flaunt the rules and brag about it openly.