I can say categorically that the PIP appeal process is designed to be as difficult and as exhausting as possible, in order to make people who already struggle just give up completely. It’s designed to be a big, impassable mountain.
‘Fit to work’ – somebody suffering from an incapacitating condition, whose heart still beats.
‘Tough’ – punitive.
‘Tough but fair’ – punitive and arbitrary.
Source: A Guide To DWP Euphemisms 2016