That's a good point, and it may net out to be an advantage for a gig employee. But is is a complicated calculation. Throw in the higher payroll tax rate for gig employees, and tax deductible healthcare expenditures by companies on employees and it is unclear there is any advantage in overall taxes paid.
Gig independent contractors pay the same payroll tax as employee/employer pairs.
Same rates, lower overall income, and in some places lower social security contributions.
They're also responsible for paying for their expenses, and i'll bet they're not as good at getting writeoffs as the in-house CPA.
So you might actually see increased revenues as a result.
Decent question though.
Their low wages due to capital capturing profits instead of labor makes for decreased tax revenue