He is making a distinction between cost to survive (I.e. food, shelter, etc) and cost to have the job (I.e. transport). "net pay is below zero" means (In his i

He is making a distinction between cost to survive (I.e. food, shelter, etc) and cost to have the job (I.e. transport). "net pay is below zero" means (In his interpretation) that the cost of having the job is greater than the amount the job pays. This is unrelated to the cost of surviving.