Of course they don't! I find it interesting that both you and
@DisneyCane both used the same window analogy. So how would this work, exactly?
A theoretical lab worker is exposed in a lab, but doesn't know it. They do normal things like travel back and forth between home and work. It's China, not the US, so likely public transportation. They visit cafes and restaurants. Shops and markets. They visit their friends, they're with their family and co-workers.
I would expect they would leave infection footprints. Some at the home side, some at the work side, some random infections in between because of encounters on public transport, in a cafe/restaurant, a friend or co-worker that lives in a different part of the city. Secondary and tertiary cluster spots, connected by the route they normally travel.
It's not just about where the virus clustered. But where it *didn't.* Yes, it makes sense that an infected person would spread the virus "near their home." But how did they manage to stop infections from occurring elsewhere in their daily activities and the encounters they would have had?