I obviously just put the cartoon up because it was topical and amusing. However...
I think that the argument, really, is that if there's no money changing hands, the pressure is relatively limited to fly. If money is changing hands, then the pressure to fly is greater, and thus the need for greater judgement and skill.
It's a healthy argument - particularly since there's not much in the CPL about judgement, and most of the skill is about precision flying. If the CPL TK was all about judgement, and the skill test all about handling emergencies, the argument would be stronger.
G