The federal government publishes its spending data[1], and that is simply not what the money is spent on.
Transportation in totality was 7% of discretionary spending, itself 24% of total spending in 2019 [1].
2020 was an unusual year with enhanced unemployment and the paycheck protection program, but depending on whether you want to count the interest on debt, 35% to 40% of federal spending was on Medicaid, Social Security, and Medicare, the latter net of premiums (so gross spending was higher).
In 2018, a more normal year, these categories represented 55% of spending, interest being 8%.
In short, most federal tax dollars represent a redistribution of income from the young and working to the old, nonworking population. That’s what the plurality of the dollars do. Whether or not that’s a “good” thing is outside the scope of this comment, but we should at least be able to be honest about it.
[1]: https://en.wikipedia.org/wiki/Government_spending_in_the_Uni...