Gather 'round, Gentle Readers, and Auntie Tam will give you a free lesson in economics.
There is a thing called "Division of Labor" that makes an economy more productive. As an example, your corner automobile mechanic needs to put a rebuilt gizmo in your car to replace the broken one. Now, theoretically he could keep trained gizmo rebuilders in his employ, as well as all the parts necessary for rebuilding gizmos, and do it on the premises. However, it is much more economically feasible to have one or two gizmo rebuilders in town that specialize in nothing but gizmo rebuilding, and have all the local mechanics use their services.
He removes the gizmo from your car, sends it to the rebuilders, and installs a rebuilt one in its place. He charges a percentage over what the gizmo rebuilder to compensate him for his time in diagnosing the bad gizmo, replacing it, and a bit of that "profit" thing which is why he started the business in the first place. Thanks to the economies of scale, you still get your gizmo rebuilt more cheaply than if the mechanic had to do it himself.
In modern medicine, a large part of its success is based on the accuracy of diagnoses. These diagnoses are made possible by a bewildering array of tests and labwork. These tests and labwork require test kits and reagents and centrifuges and gas chromatographs and all manner of other stuff that would be impractical to keep in every doctor's office, along with the technicians to operate it all. It's more practical, and cheaper in the long run, to send your test samples off to the gizmo rebuilders.
Simple, right? Apparently not. For example, this piece of Basic Economics seems to have flown completely over the head of some legislators in Missouri.
You don't have to be a vote-pandering, dumb-as-a-stump, collectivist simpleton to get into politics. But it helps.