I just think it's boring that you think money is the only reasonable motivator for these people. There are other forms of compensation and appreciation. And it's not the only option available to us. It's crazy to me that people understand the idea of countries that have military conscription but can't fathom the idea of a system of workable civil conscription.

As I see it you successfully identified a problem and a solution, but that does not suggest that that is the sole or even best solution.

When you do your scaling you need to scale everything. The adult population of the US is estimated as 266 million people as of now. Half a million is roughly 1 adult in 530 people. Let's quadruple it up so they have nice relaxed works schedule. Let's say now you need 4 people per 530. If you think you can't find 10 out of 1000 people who would do some sanitation work, with no stress and without having to think where their next meal comes from, you just never met people.
And this is the most important part that you seem to ignore - when people's basic means are met, they want to fulfill higher levels of Maslow's hierarchy of needs. For some that means doing arts or doing some engineering or running a company. For some, and there are s many of those some, that means "it's not much but it's honest work". Doing small visible changes that make the world the better place one picked up piece of rubbish at a time, is exactly, precisely what significant portion of humanity will be doing.
This also works in another direction: billions of people who would be doing something grand and moving humanity further, are stuck in mundane repetitive broken jobs they hate, because they're stuck in this cycle of needing to grind to survive, without having a moment to breath, which slowly kills every bit of light they once had a potential to have.