-Why should anyone need to provide documentation to prove they need assistance?

I concur!

Why do multimillionaires and billionaires need tax payer subsidies?

I agree with you here ...

But I assume you're taking about Stadiums, and here's why it happens; researching why the Oakland deal fell apart., the Cities want control of the project.

So if the city wants control why should the owners of the team foot the bill? The team was throwing in all sorts of items that had nothing to do with the A's.

that is why most projects become the taxpayers burden, across the board I suspect this is what happens.

Cities never if ever, say build whatever you want and we will subsidize it.

That being said, I learned to from a friend who is a restaurant owner; His refrig went dead at the restaurant, and they replaced it, sales tax 10%, on top of that there is another tax for "property improvement" of his restuarant; WTF was improved.
This is the government at work behind the scenes, sure maybe the give them a subsidy, but the asset they build is TAXED to no end. This is the shit happens behind the scenes.

I think they are called Tangible Personal Property (TPP) / Business Personal Property (BPP) taxes.

I get taxed more (forever) if I make my plane safer to fly ... If I add a new avionics I pay a 10% sales tax, then I pay an asset tax on an asset that never depreciates. Ergo I pay more every year to the government to be safer for you and me. Thats insane.

NOW thinking about the hospital that paralyzed those patients; there are automated systems but they cost $1M+ but also there is an enormous "improvement tax" the hospital will have to pay. So the hospital has to weigh the odds and chances, in this case they got hosed, and people are paralyzed, why? Some of the reason is that taxes on improvements make things like safety unaffordable.

America is fucked up with these sorts of taxes on" improvements"; they aren't every where but they are in a majority of States. The government is actively charging a tax for safety and making things better.

Lets talk about big box vs local shop ....

When a big box moves in it pays for the property and taxes. But it doesn't pay for the same rate as a mom and pop store who employees local talent to build a display case ($1000), they get taxed heavily. The big box, throw up some cheap economy scale manufactured displays, cost $100.

The BPP creates a barrier to entry to the local mom and pop. Making the country a BigBox Country. On top of all profits going to the bigbox HQ versus your hometown.

The same reason Billionaires and BigBoxes are being created is because you want to collect MORE taxes.
Its not the big box retailers fault, its the government you wanted.
You indirectly voted for the big-boxes over mom-pop. The system is working as you wanted.

Lets go with your personal homes ..

Make an improvement and you are taxed at a new assessed rate. What's the logic here?
Or make changes to your home to make it better, you add perhaps a pool or an ADU, and the government wants its increase in value forever!
Despite that you improved it with your income that was taxed already ...
Look I get when you sell it and get the government reassess ithe property, but you can't improve your property without paying the government forever.
Thats insane.

So no one does it, or they do it without being permitted, or only the super rich that can afford to.

If you follow the above, and see the insanity happening in America now ... why investment into liquid assets are really the only play.

Perhaps, but unlikely you can understand why Billionaires would move to a new state, or be against an asset tax, and why you should be too.

It constrains investment, facors BIG corporations over mom and pop, which then constrains local tax revenue for the government, by staying local.