Present day orthodox economists have much in common with the flat earth believers prior to the advent of scientific theory. They have all the information they need to describe our reality but they have invested in the status quo and would do themselves, and their benefactors, harm in acknowledging it.

Even in your protest of neoliberal economics you mistakenly relate public spending to the government's ability to tax. This shows just how entrenched the status quo thinking is. The basis of neoliberalism is the concept of efficiency of the private sector as preferable to government's inherent wasteful nature. Thatcher's most influential statement was "There is no such thing as public money, there is only taxpayers’ money." This makes the mistaken assumption that the source of all money is private sector and that the public sector must "find" money to fund its programs and provision itself.

This is, as MMT economists demonstrate, exactly opposite of our reality, especially in nations that have sovereign fiat currencies. Such nations are the price setters for their economies and can afford anything that is for sale denominated in the currencies they can create at will and independent of revenue. Taxing and borrowing, while serving their own purposes, are not funding mechanisms for those nations.

Only the fact that this goes against common assumptions from the perspective of the people as "users" of the currency has kept the politicians and their lapdog economists from experiencing the guillotine. Should the people ever have a mass epiphany concerning their economic reality, realizing that "any" suffering that can be mitigated with federal spending is entirely a political decision, not economics, that insulation from consequence may disappear. The correct answer to "How will you pay for it?" at the federal level is "Get rid of the questioner and make sure no one who would ask the question ever achieves power again".