Federal funding to help states usually involves two methods. The first is transportation block grants where the federal government gives states money to use towards transportation at their discretion within certain constraints. The other is funding for specific projects. This funding generally involves the state applying to the federal department of transportation for funds toward a specific project. The department of transportation provides these funds out of a pool of money allocated by Congress each year. Congress plays no formal role in how these funds are disbursed. The department of transportation decides using defined set of criteria.
In the past Congress would sometimes earmark funds toward specific projects. This is rare these days as most earmarking of funds is against current congressional rules.
The way I rationalize it is that despite the fact that it might be a bridge in Nowhere, West Virginia, it will likely have wide-reaching impacts. More trucking routes helps almost everything. If I'm a visitor, I'm going to use the bridge, so I should pay some part of that.
Given the federal corporate tax rate of 21%, the domestic tax numbers work out nicely if we assume approximately 46% of pre-tax income was from the US and the remaining 54% was foreign. Which seems plausible to me, though that is obviously a vast over-simplification and ignores a lot of details. In particular, the distribution of foreign and domestic deductible business expenses may not be the same as the distribution of revenues.
[0] https://www.wsj.com/market-data/quotes/AMZN/financials/annua...
Even considering all North America + AWS income together, since they paid $1.360B in domestic US income taxes that year (not $162M) the percentage would still be 8.37%, not 1.2%. That's ignoring all foreign taxes and the losses from the International segment. Do you consider a minimum 76% error margin to be "pretty accurate"? I sure don't.
Keep in mind, too, that losses from prior years can be carried forward and deducted from current income. That's part of the reason that there were no taxes paid in the two previous years; the current-year income is only part of the story. This is perfectly reasonable when you consider that $3B in losses one year followed by three years with $1B in annual profits equals no net income for that four-year period. Why should there be any income tax liability when there is no income? The alternative to carrying forward losses would be a refundable tax credit for the years with negative income to offset the taxes collected in profitable years, but that would be very easy to game.
Corporate income tax is the third highest source of tax revenue in the US, at $230bn in 2019. Shareholders also pay capital gains taxes, and companies pay other taxes as well or collect taxes for the government as well like sales taxes.
Here is an article with a nice chart:
https://www.taxpolicycenter.org/briefing-book/how-does-corpo...