Fairness here usually refers to the inequality left over after tax, not the tax amount itself. When the US is the 127th most unequal country out of 168 measured (by the Gini Coefficient), along with still having abject poverty around, it's not overly ideological to say more distribution needs to happen.
This is the kind of extreme internet Libertarianism that's dangerous in the real world. Not practical or concerned with extreme poverty through inequality, but preferring to fight on first principles, like all tax being theft (not your claim, but equatable).
I'm less concerned about the definition of fairness and more concerned about real human suffering.
Then your priorities are misdirected. The US Govt grabbing a few extra percent of billionaires' income would not reduce human suffering in any way.
If anything, the ultra-rich have been far more effective than governments at improving impoverished human lives by setting up charities and using them to directly send money to poor regions around the world, enabling clean water and food and basic health services.
The US Govt, unlike any other country, has the ability to print unlimited amounts of the world's reference currency. It also has no effective cap on its annual deficit or total debt. In other words, anything that the US Govt chooses to spend money on, it already can, with little oversight and no limits. That's why collecting additional revenue from billionaires, or any other source, has no effect whatsoever on how that govt spends (or "redistributes") money. US Govt's priorities are military, social security (which actually does keep many older people out of poverty), healthcare, and paying interest on its debt. You'll need to change the core priorities (including reducing deficit & debt) before collecting more money actually goes towards the goals you're seeking.
