Technically, they do. It is for EIC purposes. According to the IRS, "All ordinary and necessary expenses incurred in a self-employed taxpayer's business must also be reported." See IRC § 1402(a).
The EIC is based on income.
Here's a table from the IRS to show you the interaction of income and EIC:
<a rel="nofollow" target="_blank" href="
https://apps.irs.gov/app/vita/content/globalmedia/earned_income_credit_table_1040i.pdf">https://apps...>
