10 Times Futurama Made NO Sense

From the very first episode of Futurama, the show had to establish how different the year 3000 would be to a thousand years prior. The entirety of 'Space Pilot 3000' is built around the idea of career chips, which is ultimately what brought Fry and Leela together in the first place.

In the year 3000, citizens are allocated a single profession by their Fate Assignment Officer, and must stick to it for the rest of their lives. If they don't, they get fired out of a cannon into the sun.

Yet, this rule seems to be completely ignored in the later seasons of the show, as Leela becomes a TV writer in 'In A Gadda Da Leela' and a real estate agent in 'Overclockwise', Fry becomes a police officer in 'Law and Oracle', and the entire Planet Express crew become either flight attendants or commercial pilots in 'Neutopia'.

In 'The Cryonic Woman' Fry and Leela are able to use their original career chips to get their old jobs back, albeit reversed, but at no point in any of these episodes are career chips mentioned. How could the show possibly forget about one of the most important rules established in the very first episode ever shown?