Careers are a part of the game that required lots of research and balancing to get right. On one hand, there are so many different occupations/career paths in the real world that there is an almost unlimited supply to put in the game. On the other hand, we don’t want to overwhelm the player and cause analysis paralysis, where there is too much choice (and all options seem very similar).
An example of a merging career path is Finance. You can enter this career through either the Loan Officer or Credit Analyst occupation. A Loan Officer requires lots of sales experience, whereas a Credit Analyst requires a Bachelor Of Finance degree but no experience.
They merge into the Financial Advisor occupation, which only requires Banking Experience (gained from both previous occupations).
As you get further down a career path, the competition for the job increases. This means there are fewer openings and you’ll have to apply more times to get the job. Economic conditions also affect job competition, with a poor economy meaning more competition for all jobs.
Of course, the better occupation also comes with higher pay. However it also comes with more stress, and so your Fun need goes down faster. You’ll find yourself spending less hours working (but earning more) and more hours on leisure activities trying to satisfy that Fun need.