I mean, how much you get paid is usually related to how hard you are to replace. If it takes 1 week, 3 months, 1 year training, or a PHD in biomolecular engineering with 2 years of training.
They should make different amounts of money. It's an investment in people, and you have to pay them more to keep them.
It’s just supply and demand. It doesn’t matter how long you have to be trained or how many PhDs you have. Like it takes years to become a decent 3D animator, but those guys get paid peanuts compared to many other jobs that require the same amount of training. Since there are thousands of desperate fresh grad animators looking for a job every year. For every job at Pixar there is a line waiting for someone to get fired.
Also why for example plumbers and electricians get paid really well nowadays sometimes more than people with advanced degrees. Since there is a shortage of plumbers and electricians.