Tbh the solution that Sully and Mike come up is still the same system of invading another world's people and exploiting that world's youth for energy, only with added harm reduction on top that gets explained away by being more profitable. The fact that the receptionist happens to be chief of the company's militarized security force (idk if they're city cops or not, also wtf) is glossed over.

Also they just leave the yeti on the human world in the third act. Nobody comes back for him??? The guy is drinking his own piss standed in a hostile world. Its fucked up.

Edit: now that I think about it, was the Yeti a criminal in the monster world and so his punishment was to be exiled to the human world (did they fucking disappear him?) Also the present threat to the monster world is humans coming into their world (and presumably doing the same thing to them/revenge). The monster world/metropolis is a imperialist nation with a militarized police force (they brutalize/humiliate an employee in the first act when he unknowingly has contraband on him) to use the human world as a threat mechanism and source of resources for its people. Did I watch this movie too many times? Yeah probably.

Edit 2: To delve deeper on "it's just a work of fiction": Monsters Inc is a story about two everyman individuals who out the CEO of a energy firm because that CEO tried to replace all the workers with machines (in a capitalist drive for never-ending profit) and expand the imperialist system with outright war (kidnapping children). Sully is given managerial position and Mike takes sully's old job. Nothing changes from the status quo.The emotional journey of the movie is furfilled when Mike painstankingly reassembles the door to boo's house (something that movie goes out to imply that Mike acted alone with his limited knowledge). The end result is that "good people" like Sully (who was the hardest working employee before) are in positions of power and good people will inevitably be granted with positive outcomes (laughs are more energy efficient than scream by chance). Sully's good nature is rewarded in the end and the system is a better one (in a marginal way). The message the film is comfortable with is the vague protestant notion that hard work and principles will resolve systemic conflict, not agitation of already established authority or science.

In other words, the USA's supposed political ethos (The American Dream).