Why did fast food work in the United States become a career?

I remember when I was a kid, it was pimple face geeks, flipping burgers and high school kids at the register or something like that. Why did it become an aspiration to serve hamburgers and french fries to people? Don't get me wrong, I am not against the big companies paying people more, I'm just wondering why so many people aspire to only do that? The country needs nurses, police, firefighters, military, some of these have absolutely no education requirement, but people want to work at McDonald's?

Why did fast food work in the United States become a career?
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