In many states its legal for people 16-18 to work, usually with limitations on hours worked per shift/week an what kind of jobs they can do.
Even then, many older people in the US will call someone 18-20 "kids", even though they're technically adults.
As a US English speaker I took it to mean "a bunch of young and immature people, probably on their first job" when I heard "most people are just kids", not that they're literally hiring 12 year olds or something.
I can't say I know the law in every state so I typically don't say absolutes like that. If that's true, thanks for clarifying/correcting.
Also, it looks like you're right for at least the states I normally deal with. Looking back the first job I had started when I was still 15, I must have just blended those shift schedule restrictions during the rest of my time working as 16-17 as well. So yeah, I guess that's probably true.
Even then, many older people in the US will call someone 18-20 "kids", even though they're technically adults.
As a US English speaker I took it to mean "a bunch of young and immature people, probably on their first job" when I heard "most people are just kids", not that they're literally hiring 12 year olds or something.