Not always. Being in one of these low end jobs tends to beget staying in that low end job longer, making it more difficult to have the time to invest in getting a better job. Numerous studies have shown that giving people a bigger safety net may make them stay unemployed longer, but when they do get a job they end up making much more money and being happier overall.
You are thinking of people who go to college or get some sort of official training. However, the best way to earn more money is to get on the job ladder and start learning skills. Once you have some experience it’s far easier to earn more. Putting people on welfare doesn’t help people learn skills.