Many people whose income is from social security pay no income tax. A huge consumption tax would hit them hard. It would be stupid for them to want it.
Taxes on expenditures up to the poverty level will be rebated, so if you are at or below that level you will not be taxed. The details are in the legislation, you can read it yourself here...
https://www.congress.gov/bill/117th-congress/house-bill/25/text?r=96&s=1