But they do have that responsibility. They're supposed to wash their hands. That's the #1 way to stop the spread of viruses and bacteria. We also require they put their garbage into garbage cans and out to the street every week, so that the streets aren't literally covered in contaminated waste, like they were a century ago.
We also require they call the police when a crime is occurring. And the fire department when a fire occurs. And the city's department of works when a water main breaks. We also require they follow minimum driving standards and laws, take a test to certify they can drive, and make sure their vehicle passes a regular safety inspection.
"Public safety" in America is funny sometimes. In the rest of the developed world, produce and eggs don't usually come pre-washed, and you can even buy unpasteurized cheese and milk. But we Americans take so little responsibility for our own welfare that we literally force our society to protect us in every possible corner case, because taking the time to protect ourselves is too much to ask.
Except when it comes to necessities, like guns. Then we'd much rather be dead than safe.
Another fun example of how it's a citizen's responsibility to help: ending unjust laws that unfairly target people with no ability to defend themselves. Like the homeless. In many cities in America, it is illegal for a citizen to give a sandwich to a homeless person. They also are banned from many public spaces, and pushed out of the few places that they can actually have a space to rest or sleep, like highway underpasses and abandoned train tracks. They can't form a coalition and petition the city on their behalf; they don't have the resources. But we do.
We also have the resources to vote to install more shelters, more food banks, more outreach programs, more clean needle exchanges, more job programs, or hell, even just a place someone can have a shit and a shower. We have the resources to vote for programs to help hire homeless people, and to vote to expand low income housing. We have the resources to vote to distribute blankets and food during the winter, and expand safe spaces for more vulnerable homeless like women, children, LGBTQ youth, and so on. There's a lot of things we could do as citizens that wouldn't require you to actually do anything other than check off a box on a ballot, and maybe fork over an extra $1.50 in local taxes.
That's the least a citizen could do, but I don't see that being done either.