Federal Income Tax on Non-Profits?

The nonprofit industry includes over 1 million organizations across the US with combined annual revenue of more than $1 trillions. Major organizations include Goodwill Industries, Ascension Health, National Cancer Institute, New York University, and the Bill & Melinda Gates Foundation. The industry is highly fragmented: large organizations with assets of $10 millions or more represent just 6 percent of the industry but account for more than 80 percent of the sector's total annual revenue. A modest annual federal income tax of 2% on those organizations with + $10 millions in assets would thus generate in the neighborhood of $16 billions. A more realistic tax similar to the "corporate income tax rates" would generate some $272 Billions. That's roughly equivalent to 5 times the total annual budget for the State of Illinois. These companies pay Social Security and Medicaid/Medicare taxes. They pay other federal taxes. Why not an income tax?