At the start of the game, cims start off at home and are assigned a job if one is available. Then the cim drives into town, goes to their residence, then tries to go to work. If it fails, it despawns back home and tries again and again until it makes it to work.
The consequences are purely the traffic it generates. Soon all of your roads are full of traffic and no one can get anywhere and your city starts falling apart.
As mayor, you need to balance out your districts so cims can get from point A to point B in a timely manner or bad things will happen in your city.
But this game is purely about managing traffic, not getting cims to work. Getting cims to work is purely a gaming concept to make the game appear more realistic and adding traffic to the map so your city looks alive.
The game part of this is trying to figure out where cims want to go, and get them there on time.
As for cims, there are different types. As discussed, workers need to go to work. There are also Tourists that come in from off the map and only go visit your tourist attractions (unique buildings, parks, and commercial) then go bak off the map, local shoppers that want to visits businesses.