I'd argue that in our quest to maximize income inequality, we've made many necessary careers non-viable from a living standards perspective.
These non viable careers include pilots, atc, teaching, and a large portion of the skilled trades and more. While a non viable career path will still have some individuals in the field due to sunk cost, passion, or inertia - a shortage is inevitable.
Supply and demand should rationalize this - but if training is long, wage visibility is low, and sunk cost is high, and negotiation power is low - its entirely possible for a employers to collectively push the prevailing wage below the level which makes the job worth it to enough individuals.
[1] https://www.natca.org/2015/12/09/natca-discusses-air-traffic...