There are many programs which together provide a significant economic baseline. It's not all in the form of direct cash deposits, although much of it is, it's just that the programs are a disparate and tangled mess. That $40k trucker's salary nets out to only about $5k more than the baseline benefits for an unemployed adult citizen. [1] It's barely better than not working, and you have to spend the whole week on the road! Staying home and fixing up the house [2] while taking the subsidies will always be a better bet.
The only difference between what we have today and "Basic Income" is currently we phase the benefits out as you start to work, obviously to disincentivize working. You could think of "Universal Healthcare", for example, a lot like eliminating the phase-out for Medicaid. ACA already eliminated the asset test, now it's just an income test, so maybe that will go next. (mostly depends who's elected in 2016)
[1] http://www.cbo.gov/sites/default/files/11-15-2012-MarginalTa...