Just in case you missed it: (emphases mine)

Which employers may use the youth minimum wage?

All employers covered by the FLSA may pay eligible employees the youth minimum wage, unless prohibited by State or local law. Where a State or local law requires payment of a minimum wage higher than $4.25 an hour and makes no exception for employees under age 20, the higher State or local minimum wage standard would apply.

You wrote,

Which is a buisnesses that makes less than 500,000. But those buisnesses also cannot engage in Interstate Commerce per federal law. In the modern world it is nearly impossible to have a buisness making any amount money that does not engage in some form of Interstate Commerce. So functionally that exemption is meaningless.

I am well aware of what that means. I think that you are not. Check out what the DoL has to say about businesses and individuals not covered by FLSA: there are plenty of businesses that do not meet the standards but have employees that do, for example.

You are really reaching when you insist -- incorrectly -- that Montana's exception has no real world meaning. I assure you that exception was very specifically placed in the law for a real world business' benefit, and that that business had pull in the state capitol or it would not have been added, just as the FLSA itself provides for those exceptions to be made by the states.

If you can't be bothered to educate yourself on what "interstate commerce" means in the federal legal sense, that's fine by me because I've provided links for all of my assertions, unlike you: people can read them for themselves.

The FLSA has carve outs for various kinds of employees, and while minors are covered, they are not covered as adults are:

The 1996 Amendments to the FLSA allow employers to pay a youth minimum wage of not less than $4.25 an hour to employees who are under 20 years of age during the first 90 consecutive calendar days after initial employment. The law contains certain protections for employees that prohibit employers from displacing any employee in order to hire someone at the youth minimum wage. -- from the DoL page linked below

In addition, only a handful of states actually ban subminimum pay for minors, requiring by law full minimum wage. You wrote,

An individual state law cannot supersede federal law.

That is where you are flat out wrong. When it comes to minors and other special categories of workers, they can and do.

Here's the DoL page on that, you should read it:

Fact Sheet #32: Youth Minimum Wage - Fair Labor Standards Act

Here's another page that lays out what that means for tipped minors. Quoting from further down in the page:

State law prevails: If state law is more restrictive than federal (higher youth wage or no youth wage), you must follow state law.

Again, that's why I linked the table. It's a complex maze of laws and conditions. And I didn't miss this. You wrote,

You did skip a few types of employees that are actually exempt like movie theater employees.

That's because I did not expect someone to fight so hard, with such incorrect and easily disproved assumptions, in defense of such a shitty principle: not paying servers a living wage.