I feel like the USA is not prepared for the 50% unemployment rate it's looking at when the value of labor in many industries drops to pennies. Other countries with safety nets and socialist programs can probably switch to a UBI style economy or simply communism, but the USA is so allergic to such things I don't see anything other than chaos and collapse. And they have allllll those guns too...
Where does that UBI money come from if there are 50% fewer people paying taxes? That's the problem.
But yes, you're right, the core problem is that in the USA, people need to justify their existence through labor. If they can't labor, they can't justify their existence (barring the slim few outliers on benefits, who are constantly under attack for being lazy or whatever).
However, if we take a step back and just consider reality for itself, we're just talking about resource allocation. Under the current system, the allocation of resources is dependent upon how much cash any given person can command, which is ostensibly connected to the value of their labor, but in reality, is clumpy and is connected first and foremost to how much cash they or their family historically had, and secondarily how valuable their labor is to capitalism, rather than to humanity. Thus investment bankers make 9x what teachers and EMTs make.
There's no reason we need to play that game. We can simply allocate the resources along more efficient terms, such as, taking the robot-harvested food, having robots put it in self driving trains and trucks, and having it delivered to people who need food.