I've been thinking about this since I was in a similar position only just a couple of years ago.
When I was a kid and you walked into a McD's, most of the people working there were teenagers or college students. The purpose of these jobs was to get a bit of spending money, or help pay for tuition. They were short term jobs. The only adults you saw working there were either folks who were really hard up, or had absolutely no ambition.
Today you don't really see teens working in these places anymore. I don't think it's because they're any lazier than they were 20 years ago. It's mostly adults working in these places. College grads, seniors, new immigrants, former factory workers.
When I worked at the car rental, we had this guy on our team working as the weekday shuttle driver. He had lost his job as a valve fitter in the recession. Went from making $30/hr to $9/hr. Used to call him Surly Steve because he was just perpetually in a bad mood. Can't blame the guy. He had a kids to raise too. Honestly don't know what happened to him. He quit one day and we never heard from him again. Had another guy on the counter who was a talented software engineer. He did get a job eventually, but it took him a year.
These were skilled workers. They eventually get replacement jobs in their fields but it takes a long time to recover them.
The recession quickly pruned out a huge chunk of unskilled labour jobs. Prior to then you could work in a factory for $15-20 an hour and make a decent enough living to survive off. It doesn't help that a lot of desk jobs now require a university degree, when they didn't just a couple decades ago. The government spent billions trying to create new jobs for these people. While most of them have been replaced, they're mostly minimum wage retail or fast food work.
It's very difficult to live off $15,000 per year. That's assuming you can get full time work. Though few places offer that today, even in professional fields.
A big part of the problem is the government can only create government jobs. They cannot create private sector jobs. All it can do is pay to retrain people or hire them on public works programs as was done during the Great Depression. The only thing that pulled us out of the depression was a shortage of labour (due to men going to war) and rich government contracts (for war supplies). Which triggered the post-war boom. America was a leading industrial nation at that time. I think a lot of people thought the good times would keep rolling. The economic downturn in the 1970s should have been a wake up call.
Now a lot of jobs have moved to China where labour is cheaper. For the Chinese, most get a decent enough wage in the factories. More than they would farming, and plenty to live on. But far less than what unionized American workers were making.
The problem is that having too many minimum wage workers are bad for the economy. They don't spend money on surplus goods and many of them collect social assistance, and many more don't pay taxes. This makes them a big drain on government coffers. The real tipping point will be when you have more people taking money out of the government than putting in, to the point where interest cannot be paid on the national debt. This is what happened in a lot of European countries. However, the likes of Walmart and McDonalds don't care as they sell goods that low income people either need or can afford. They'll make money no matter how bad the economy gets.
I think what we will see is an even greater push to unionize these jobs. It's becoming inevitable, and the big unions have been salivating. They've been wanting to dig their claws into the likes of Walmart for years, and the conditions are becoming right for it. Which IMO will be the worst possible outcome as it will significantly raise the prices of literally everything you buy. The only people that really win that battle are the unions, financially speaking.
Honestly, I don't know what the solution is to this problem. I don't think anybody does.