20% of $400 is still not all that much unless you're in abject poverty. For a minimum-wage worker in the US, it's a little over a day's work, but for anyone else, it's vanishingly smaller. For a person on a median income (around $27.5k in the US), it's only several hours work. For a higher-level professional, it's not even an hour's work. $80 doesn't buy you a lot of professional time.

$400 certainly isn't three months income in the US (~$6900/qtr is the median), as suggested earlier in the paragraph, let alone the 20% split of that.