Because you have to actually work hard to make money in those jobs. A lot of people when faced with the decision between being lazy and skimping by in life, or working hard and living comfortably will pick the former.
This is nonsense. No one takes intensive jobs unless they have to in order to achieve something. In fact, no one takes on any other more work unless there's an incentive that would motivate them to do so. You don't use a wagon over a car, you don't grow your own vegetables over going to the grocery store, and you surely don't consistently cook your meals over grabbing food at restaurants.
Laborer jobs are for people have no other skills to offer. You're not going to take a dangerous job over a more comfortable, less stressful job unless you want to. And take it from me, someone who pissed off my entire family and friend circle for walking away from a $40K salary job with benefits to go flip burgers. Why? Because I wanted to be a cook.
This is the logic of someone who thinks flipping burgers actually connects to being a chef. Bad logic. ---