No mostlyharmless, either no one thought it through or they did and don't give a ***.
There is a sad bit of me that feels they did know, how could they not unless they genuinely do live only amongst the wealthy and never meet a constituent who is one of the hardworking poor/the sick/the ill/the depressed, anxious, on the ASD spectrum, suffering from diagnosable mental or physical health problems that make working full time on minimum wage, or on a zero hours contract - or so many other "things" that mean an individual and possibly their partner and children are dependent on benefits.
As JessM says, for the few, not the many.