Some jobs - you can do anywhere. If I were to take my chocolate business to another location, state or whatever, as long as the company allows it and has shipping to the location, all I'd need to learn about would be different tax rates on purchases. No big deal!
But if you are an attorney tucson, for example, you can't just up and move somewhere else. Attorneys, nurses, and other professions certified by a board usually require state-specific knowledge. I've been seeing a lot of this in proofreading some documents about law in Michigan. The details are nuts, and I'm just reading them for spelling, grammar, and consistency from post to post or section to section!
When I think the knowledge is overwhelming, I'm grateful I don't have to learn it at this point in my life, but on the other hand I do remember learning the laws that applied to my jobs in banking, collections, and debt management, in particular. It was stuff that just became so ingrained I didn't really have to 'think' about it much by the end. I am grateful I never tried to move or do anything else to change what I was doing mid-course though!