The Simpsons operates on a uniquely flexible approach to its static continuity. While the specific dynamics of the show rarely change, the characters have gone through all sorts of growth and development over the years. This extends to their professional work, which has seen both Homer and Marge take on a truly absurd number of jobs over the show's decades' worth of episodes. Oftentimes, these are throwaway gag jobs, but they sometimes come with far more important roles within the ecosystem of Springfield.
Source：https://www.cbr.com/the-simpsons-homer-marge-better-springfield-mayor/
