Read the actual decision.[1] The discussion of this issue starts at page 62. The Court discusses why there should be a distinction, and why it needs to be less ambiguous than the "multifactor test".
The closest it comes to addressing my points is when it talks of “evading wage and hour” laws. But that’s my point: Why do you count it as “evading” anything when you buy labor from someone who offers it as a freelancer, and that rate is under the minimum? What desideratum does that violate? Why do you let anyone offer services, at all, in any capacity (including as a business) when they might earn less than minimum wage, or even negative amounts?
It is being abused though to offer full time jobs for reduced pay or for tax benefits to the company.
Working for less than minimum wage is against the law. Are you actually suggesting that minimum wage is a bad idea, and so of course the rest wouldn't hold up. In this case, a minimum wage is considered a premise of the entire decision.
I cannot see an issue about gifting people something. I do see an issue with allowing paid work at less than the legal minimum wage, which I expect is why this was framed as an evasion of the wage and hour laws.
To go very off topic, my quick reason for why minimum wage laws are desired is as follows (note I don't think any of this works as follows in real life, but this is the reasoning I can come up with):
We as a society do not actually want to subsidize businesses where they shunt the cost of their employees to the public but privatize the profits - i.e. if Walmart only "makes money" because the local governments have to pay 1/2 the employee wages in poverty avoiding benefits - we don't want Walmart to succeed. So we set a wage minimum in law where if you make that amount society thinks you wouldn't need welfare etc. It may also be seen as a moral value that an employee should make enough to survive at a job. I.e. we should treat employes "this good" in a developed country.
No, it's not. You can absolutely set up a proprietorship, and sell labor, such that the pre-tax proceeds per hour of labor are less than the minimum. That is legal. It's just not legal for an "employer" to be the payer of that income, hence begging the original question.
That's my whole point: why does this distinction exist?
It's pretty trivial to defend any tiny part of the system in isolation. The problem is to explain why you have this employer-contractor boundary. That needs more (as justified in my original comment) than "I don't want workers to be oppressed" or "I don't like businesses shunting costs onto the public".
These confused rulings are exactly what you expect in the absence of such a mooring. They can't give a reason why my rules A or B are absurd, except for whether they match some hard-to-parse guidelines.
Example: If the employer requires you to bring your own tools, that somehow makes you more of a contractor, even though that's a greater burden on the worker, but someone decided that such instances "feel" more like contractors. Exactly what confused governance and legislation look like.