It is not.
It is, instead, that separately means-testing individual programs is at best wasteful duplicative bureaucracy, and often has really dumb effects even in the cases where the individual programs in isolation don’t have cliffs or other perverse incentives when the means-testing of separate programs is considered together (such as totally to > $1 in lost benefits for each $1 in additional income.)
Progressive taxation is, inherently, universal means-testing which, because its all in one spot, can more easily avoid either slipping a bad incentive through in an underobserved program or creating a non-obvious bad incentive in the aggregate of programs.
That’s why the U is in UBI.
Also, not all "means-testing" is made alike. They are not all equally bureaucratic. You could easily do a negative income tax that is basically automatic.
“Negative income tax” is literally just another (older, in fact) name for UBI.
In UBI everyone gets the same amount of money. NIT would work basically like how paycheck withholdings work for income tax, just that they can go negative and the government can pay you based on income and exemptions. The only trick is that you would need the equivalent of a W-2 for anyone in America eligible for the program.
I suppose in some cartoonish parody of MMT dreamed up by conservatives to scare children you could a UBI with no tax system that wasn’t functionally identical to a NIT, but that’s not what anyone is proposing.
> The only trick is that you would need the equivalent of a W-2 for anyone in America eligible for the program.
You need W-2s for the same set of people you need them for already (those with the kind of income reported on a W-2.)
But I think we are on the same page. If you file a W-2, you are probably going to withhold income. At which point they are functionally the same.
If your goal is to reduce inequality, means-tested programs are much more effective precisely because they don't cause demand-pull inflation. The recipients and amounts are few and small enough that supply flexibility is able to absorb the increased demand.
If everyone gets a benefit it will cause inflation and then you're back where you started.