In my town they have a snow blower on a small tractor trying to clear walking routes to school. But there always places it cant handle such as a narrow spot or tree or post obstructions on the sidewalk. Maybe a car not pulled in far enough. Kids have to walk in the street until the constriction is passed, unless someone shovels

I’m sure the same is true in nyc: various machinery in most places, but some just can’t fit a machine for various reasons.

Note that they didn’t hire millions of shovelers. If they didn’t have machines doing most of the work, they’d still be shovelling