That is not how marginal tax rates work. I’m not suggesting we abandon marginal tax brackets. In the case of your example, the person who earned $101k would pay tax on the $1k above $100k, i.e. they would pay $200 of taxes.
The proposal to start taxing only amounts above $100k is not fundamentally different from the standard deduction or personal allowance that already exists (YMMV by jurisdiction). My proposal is simply to increase this floor by 10-20x.
There aren’t many tax schemes in the world where earning $1 more incurs > $1 in tax. Ironically it’s more likely to happen if you’re poor, and a gain in income causes you to lose social support or other benefits.
It's never that simple. Serbia still to this day has a scheme where you get a fixed amount taxation as self-employed "enterpreneur" up to 6M RSD (50k EUR/60k USD) of revenue, but are subjected to other taxation rules once you cross it (as a company or as an employee). It was heavily (ab)used by the IT crowd locally (until rule changes in 2019 about who can use this), and it was beneficial to stay under the 6M limit or you'd need to approach 10M (100k USD) to get the same net income.
The proposal to start taxing only amounts above $100k is not fundamentally different from the standard deduction or personal allowance that already exists (YMMV by jurisdiction). My proposal is simply to increase this floor by 10-20x.