Each of the SuperCities has their own niche in the market. They have grown to support and focus on that skillset, even teaching it in some schools. Having originally grown out of Detroit the manufacturing capacity of this region was magnified and unified into a single stream of production called The Pit. “Chitroit fills the skies” has replaced the Motor SuperCity as its moniker and business is going well.
The Pit is a large and complex sector of Chitroit that contains about 60% of the FTL engine manufacturing capacity on the planet. Work there is hard, but plentiful, and the market is ever growing. The really specialized or exotic engines are still being made in Tokyo, but their market share shrinks every year as they cannot keep up with demand.
One interesting fact of modern life is that almost no one starves to death. There may not be steady work for everyone, or even most, but almost none go hungry. Engevo has gone so far as to solve hunger, all the supercities have an extensive network of interconnected soup kitchens. Called Sludgers, these largely automated service centers give away a nutrient rich algae mash for free to all comers. It tastes like the pipes it is pumped in, but it will keep you alive indefinitely. This is the baseline for life on earth, simply that, sustenance. It is your duty to contribute, it is your duty to be part of the expansion of mankind. Should you succeed your reward will be a better than average life. As with any system there are those beyond the norm, some of the slums have population that cannot reach the Sludgers on a regular basis. Those few that live outside of the cities endure a constant struggle for survival.
Life on earth is made possible by work in deep space. Between two and five percent of humanity is not on earth at any given time. These are the explorers, the roughnecks. Pilots, miners, excavators and profiteers search the stars. Life on the frontier is civil if not cordial, and there are plenty prefer it to life in the stacks, but it carries somewhat more risk. There are as yet no alien threats in our space but our own kind can be vicious, casualties are light and piracy is not yet rampant, but growing. The incredible amounts of money to be made in space exploration and resource recovery have prompted a significant uptick in security but there are always those enterprising souls.
A significant gray market exists below midstack in most cities. What used to be the middle class struggles with daily necessities like housing and work, so semi-legal means have grown in popularity. Providence manifests for gear like air strippers and service droids are rarely checked, and reuse and recycling are common. These people are often forced to split their time between as many 0-hour jobs as they can bid their time on. These jobs are slowly falling, one by one, to robots, but the day they can teach a robot how to put together a good, custom latte is far off.