Well, how does it work for taxi drivers employed at taxi companies in Germany then?

Mandatory minimum wage, mandatory health insurance, mandatory retirement funds, mandatory unemployment insurance, etc.

Yes, in the end they usually get nothing for doing extra work (just their wage, plus 0€/mile), but that’s most definitely better:

The risk is gone – you don’t have to worry about medical stuff, or anything anymore, even as McDonalds fastfood drone you still have insurance, etc guaranteed.

I get the benefits of having benefits. But even in Germany, independent contractors are "a thing", and there are at least some workers who don't have their employer/main client directly paying for their benefits. And for (at least some of) those cases, we can recognize that it's pointless to make that main client pay for their benefits. Some workers believe they are better of by having contractor status and buying their own benefits, and you would need to find a compelling reason not to let this happen; that's why I'm asking for the logic behind the mandate against it.

When you think someone is flouting a reasonable law, that should directly translate into "here's a collective action problem whose solution they're disrupting".

"X should not be allowed to pollute at Y levels." -> "There is a collective action problem of preventing damage to the environment, which requires that everyone pollute less than Y, even though people privately benefit from doing more."

"Hans should not be allowed to pickpocket the wallets of passersby." -> "There is a collective action problem of ensuring stable property rights, which requires that people respect others' possessions, even though they privately benefit from stealing."

"Uber should buy health insurance for drivers." -> "There is a collective action problem of ????, which requires that Uber buy health insurance for drivers, even though they privately benefit from paying them cash instead."

Note 1: your answer to ???? must not be so broad that it proves you should buy health insurance for every person you buy a service from, including e.g. the independent courier that delivered your package.

Note 2: I made an honest attempt to unravel the logic of "what is the law accomplishing with the employer/contractor boundary", in an attempt to answer that question, in this post here: https://news.ycombinator.com/item?id=10717768

If you have a better answer, I'm very interested in learning from it.

Well, the German society has decided that yes, you should buy health insurance for every person you buy a service from, including the courier.

The result is subsidized healthcare via a complicated and weird system.

In fact, in Germany the employee always pays the healthcare insurance themselves as solution, but the government subsidizes it.

Sometimes the situation is that, yes, everyone should have something, so the employee/contractor divide makes no sense.

In the Uber/Lyft situation, the drivers should have health insurance through the government, and the car should be insured during the ride or between the rides by the companies.

The issue was about whether you should have to directly buy that courier's health insurance, and German law (as you note) obviates that question. (Though it didn't help to blur the difference between directly buying the courier's insurance vs indirectly via taxes, which was the core distinction the discussion was making.)

So I don't know why you (earlier upthread) thought that the German practice provided any insight into how to resolve the issue, given that US forces some purchasers ("employers") but not others ("customer") to provide certain benefits.

The German model does, however, provide a clean way to "cut" this "Gordian knot".