It's important to know that not all income is taxed in the US, there are a host of deductions that can reduce taxable income. At the minimum most individuals would benefit from the standard deduction of $12k (or $24k if married filing jointly). If someone earns $500k and donates $200k to charity, they don't pay income tax on $500k of income, they pay on $300k of income because charitable contributions are deductible.
Next, as Bob already pointed out, it's a progressive tax system, so if you had $500k of taxable income you'd pay $150,689.50, which is actually 30.1% tax rate. You would however be taxed 37% on each taxable dollar over $500k.
We also have a host of tax credits, some of which are refundable, that basically count as tax dollars paid. For example if I owed $6k in income tax but spent $20k to buy solar panels for my house last year then I'd qualify for a $6k solar tax credit and I'd now owe $0 income tax.
One more bit is that we have different tax rates for different types of income. We have capital gains which are taxed at different rates than ordinary income depending on how long you held the capital that you sold for gain. So if you sell stock/property for a gain it isn't necessarily taxed the same as income from your job.