Some conservatives (and liberals) have argued for UBI. The devil is in the details. The conservative plans are, as far as I can tell, a way to entirely substitute the existing US welfare system with UBI... a substitution that isn't quite palatable to liberals.
On the right, UBI has been endorsed by the likes of economist Milton Friedman, former president Richard Nixon, and libertarian pundit Charles Murray. On the left, Martin Luther King, Jr., former Democratic politician George McGovern, and the Green Party have all championed the idea of the government giving each citizen a certain amount of money on a regular basis—no strings attached.
Conservatives tend to see UBI as a strategy to replace most of the existing welfare state wholesale. Nixon, for instance, proposed a basic income for needy families as part of a plan to overhaul the New Deal-era welfare state.
The problem, of course, is that a UBI would be incredibly expensive. Robert Greenstein, founder and president of the Washington, D.C., thinktank Center for Budget and Policy Priorities, estimates that a $10,000 annual basic income would cost more than $3 trillion per year, consuming nearly all of the tax revenue that the government currently raises. A UBI of this scale would either crowd out most other social programs—the conservative wish—or would require ratcheting up the federal government’s tax collection.
Murray endorsed a basic income in a 2006 book, which proposed to scrap all existing safety-net programs in favor of a $10,000 yearly grant to each American adult. Bernstein objected, anticipating that the poor would be made worse off, and defending the safety net’s gains in fighting poverty.
Murray’s basic income looks a lot like a $10,000 Trojan horse. He explicitly rejects any additional government support for families with children, and would refuse any further public aid to those who fall in need after exhausting their income grant. Those with such misfortune, Murray says, must depend on charity.
Liberals like Bernstein are right to resist this sort of basic income. Murray’s plan would voucherize the entire welfare state—a buyout in exchange for unwinding the federal government’s social-insurance obligations.
In fact, getting government out of the business of providing beneficial services and instead cutting a flat check would mimic the corporate cost-control tactic of moving workers from defined benefit packages to defined contributions. This would complete the decades-long conservative push to reform our social insurance institutions by shifting risk on to individuals in order to promote personal responsibility, as Murray aspires to do with a UBI.
From how you describe Andrew Yang's proposal, it sounds a lot like those conservative (substitution) proposals. On the other hand, you may have misrepresented it somewhat, since some of the comments argue that he is planning to raise new taxes to pay for it... which wouldn't make a lot of sense for a pure substitution. I don't feel inclined to dig into his platform, but you now know what traits to pay attention to in terms of conservative vs liberal UBI proposals.