be interesting to know what they failed on at the initial test,
my guess would be
1,head light aims - not part of servicing?
2,bulb failure - customers not checking
3,incorrect headlight pattern - customer fitted incorrectly.
4,front tyres below 1.6mm - worn inner edges - tracking not checked,and again customers not checking their tyres.
5,washers not working - customers not topping up reservoir.
as tony said,"they do not understand their part in the maintenance process"
could go on & on..........