An Individual Taxpayer Identification Number (ITIN) is a tax processing number issued by the Internal Revenue Service. The IRS issues ITINs to individuals who are required to have a U.S. taxpayer identification number but who do not have, and are not eligible to obtain, a Social Security number (SSN) from the Social Security Administration (SSA).
How are they paying though? That requires some kind of identification.
Their employers pay taxes on their wages through their fake ss numbers. They pay sales tax when they buy things from the store
https://www.irs.gov/individuals/individual-taxpayer-identification-number
Perhaps not income taxes, but maybe taxes on goods and services, property taxes, etc? Can’t say for certain though.
If you don’t have an SSN then you still need to pay income taxes via ITIN. You don’t want to be caught for Tax Fraud as an immigrant.