Honestly city RPGs should focus more on being fun instead of realistic. People like to make progress, they like to see numbers go up and giving them things to do besides building and killing will keep people in your server for awhile.
Add more specific jobs that have nothing to do with crime or law. Have fast food jobs, or taxi drivers, or sport jobs such as basketballers and footballers, or janitors that get money from cleaning. Focus less on jobs that require you to be a richard to somebody, this always ends up driving people away.
Have more rewards for playing the game longer. Maybe set it up so you can buy special things like paintings or statues or other prizes, maybe have special vehicles you have to buy to spawn for bragging rights.
Make advancing in a career more difficult, instead of just buying a new job, set it up so you have to get education and experience, or something. Make it so more advanced or technical jobs have a chance of not hiring you based on your stats, giving players an incentive to learn and get more experience.
And finally, a lot of city rpgs have bullstuff rules and dumb admins who are more focused on finding people to ban instead of trying to make the server better. Only discourage people from doing things that will ruin the fun for others, there's no point in scaring people.
