Though the non medical ones you mention can generally be handled by insurance. That usually is not tied to work. If you have a year’s savings you can generally afford insurance.
They’re tied to their jobs because healthcare costs so much. It’s unaffordable to pay $400+ per person per month plus up to $8k for out of pocket max which resets every calendar year ($16k for family) without having a job.
The $400 per person is for a young person. It goes up to $1,000 per month as you get into 50s/60s. So if you’re being prudent and factoring in the probability of not having income in your 50s/60s (age discrimination, disability, obviated from automation, outsourced), then you also need to save to plan to pay at least $12k a year in today’s money plus out of pocket maximum.
That's another thing - aren't most of them in at-will employment? Meaning they can be let go with almost no reason with no notice at any time. That's also going to put a dint in the savings.
That assumes no unexpected expenditure though? Any medical emergency (and even a lot of non-emergencies) in the US (from what I've seen) would blow those savings quickly. Also car problems, child problems, storm damaging the house/apartment, any number of things can swallow those savings quickly and you're back to square one.