How did people survive before 9-5 jobs, then? Or, more drastically, before the beginning of agriculture? (Honest question.)
TLDR: A regular schedule is just drilled into your mind. It is much more important how much you work (if there are not very good reasons for the schedule).
You are projecting your very unique and overachieving situation onto a world which is in quite the opposite position. The vast majority of the people that will end up in work programs have at best a high school degree. Many of them not even that and possibly some criminal or drug history. Or bad employment history.
~80% of the employment in the US is in the service industry. That is where most people are going to find employment.
These programs are not designed for PhD students they are designed for people who have had a hard time getting the basics straight like holding a job. Staying on the right side of the law. And making the right choices which You and I take for granted.
I know some people who are unemployed for a long time and/or have trouble getting a job or not getting fired soon after they get a job. I respect their problems. What I will never accept is why they aren't using the lot of free time that they have for example to learn a foreign language, learn computer programming or something similar. It's not that money is the problem: For language learning there is Duolingo or Memrise, for web programming there exists freeCodeCamp, etc. It's also not that there is a lack of people that they could ask for help if they really needed it: For programming or mathematics they could ask me if they really have trouble understanding, for language learning I would be willing to help them finding people they could ask etc.
I can accept that people have bad luck and end up in a shitty situation. But as I see it, many unemployed people are simply lazy.
Willpower is a very hard thing to master. Procrastination is a part of everyones life. Distractions are everywhere. People get sucked into watching TV. Playing sports. Video games, gambling etc, etc.
Also depression can be a big part of it. People get depressed and that can be very debilitating. Many people do not want to admit that they are depressed and would rather just shut themselves off from the world.
Some very smart and wealthy people end up dropping out of university or loosing all of there money and sleeping in the streets.
For some people that might end up in a work program simply having the responsibility of getting to work on time and having some obligations gives them a sense of order and purpose that can turn around there whole perspective and set them back onto a productive path.
More than 1/3rd of US adults are obese.
I agree that for some people routine would be helpful.
People underestimate how important this is. When you are out of work people have a tendency to adopt sporadic sleep habits and lifestyle. It can be a big shock just trying to get up at a set time each day and getting to specific place with the expectation that you have 8 hours of work to do.