Payroll taxes are inefficient as they discourage work and increase its cost for employers, leading to lower hiring. If payroll taxes vanishes because of AI, it doesn't mean that we should stop using it to increase productivity, but rather reorient taxes. For instance, land value tax or consumption taxes are often seen as more efficient and fair, depending on their implementation. They also are AI-proof.
The problem with consumption taxes, as we have seen time and time again, is they disproportionately affect those with lower incomes.
If anything, there’s plenty of literature showing that social programs and tax exemptions on the poor make underpaying them possible to begin with. Walmart couldn’t pay $12/hr. if tax exemptions and SNAP and other aid didn’t fill the gap.