Job is one part of life. A human is not like a variable in program that can be refactored into another class as needed.
What you are saying would work perfectly for a young college graduate, without much family or friends, who has no dependency or no one dependent on them.
Now imagine a young single mother or father that depends on their family for babysitting or caring for the child while they try to become functioning member of society.
Imagine someone with some health condition that needs access to certain medical facilities.
People live in cities and migrate to cities because they can access schools, colleges, entertainment, public transport, medical facilities, better opportunities, parks etc etc. They can't just pick and move and uproot themselves.
I think people who work in technology do not have enough exposure to the poor and struggling members of the society. I grew up in a really really poor family and when I talk to my coworkers it is very apparent that they don't understand poor people.
Even moving somewhere else within the same city is a lot less hassle if you are less concerned with immediately having the work part of the equation figured out.
I am not a young graduate, uprooting now would be a big deal for various reasons. Neither are my friends in their 30's raising families - some of which are living with their parents for the kind of reasons you describe.
My point is that without being so close to the financial edge all the time, even less well off families can take a step back and make decisions that work best for the future. The stress associated with risk (like quitting a job) results in a scary amount of lock in for many people I know.
