Explanation: Not cities in general, but the city of Rome, specifically.

https://en.wikipedia.org/wiki/Secessio_plebis

These secessions happened when Rome was still a single city rather than a massive, sprawling polity, so labor mobility was at a minimum. Lots of borders, both political and cultural. The seceding workers could not be replaced on short-notice, even at increased cost, or by temporary hires. No sending messages to a hostile neighboring city-state asking “Pretty please let us hire some of your filthy poors, even at double normal wages 🥺”; you have to work things out with the workers you have before the crisis devours the entirety of your wealth!

Secessio is a great start to a proud history of workers fighting for their rights, but history tends to clean up the details.

I always wonder how many scabs stayed back in Rome.

Truly impressive that they managed to organize that! I wonder if it would be easier or harder today; I’d asumme that authorities would be quicker with arrests and beatings these days if you organized that, plus the “seceding plebeians” have to go somewhere - you can’t just hide an entire city’s worth of workers these days and wild camping is illegal in most places.

Might be different in less developed countries.