I know it was rhetorical but define "obligation" and "have". Obligation in a moral sense is a matter of opinion. In the practical sense: What happens if the obligation isn't fufilled? Piano tuners are of lesser importance than teachers in terms of consequences for lacking entirely.

There are alternatives for everything with their own price. Even if it is horrific like "die of rabies instead of getting vaccinated after being bit".

If availability of workforce in a broader area is high but in city housing they afford is low either they need to be paid more or traffic and commute time will increase and make the job less desirable which may affect skill level and harm labor availability. Underserving is technically also an option but there will be knock on effects - if the schools are bad then parents will be more likely to relocate.