See, now that you've said you won't release it, people have kinda lost interest. Not to continue my ranting, but, people aren't concerned with it if only a couple set servers are going to have it. And I urge you to consider that, even if you don't change your mind.
As for the Mayor thing, I honestly think it's a bad idea. /Ty's edit has a mayor system and it frankly sucks. Someone is made mayor, because SOMEONE has to be, and then they don't do the job well. Then, when they leave the server, the server simply goes without, unless enough people pay enough money to impeach them. In that, it's kind of a vicious cycle. I think it would be better to have the taxes either dynamic to the economy, or supply and demand of city resources, or just simply host controlled. Having a player elected as mayor just means you'll never consistently have a competent mayor available when you play.
Now, I would like to impose another idea on you. A criminal idea. As you likely know, in /Ty's economy system, certain actions can increase or decrease the overall "health" of the economy, which then influences the paychecks people get. The point of the mayor, is they get paid a whole lot, but they are expected to donate that back into the economy to keep it strong, and if they don't, they are subject to impeachment. Though ignoring the mayor factor... An economy system like that could bring us a few more possibilities for criminal players.
So, you didn't like my earlier check card idea because it would take away from the criminal jobs, but... Picture this. Banks, require a custom modeled and fairly large vault brick. It could be a big square, with a vault door modeled on the side, allowing that lot to store the money. Players could make these vaults for their own backs like you already want to have, but... could also serve to function for the criminals. So, you have the vault. It serves to give an aesthetically pleasing aspect to your banks, and makes players who build their own vaults need to be more considerate of their designs. And if need be, you could have different vault sizes, with respective levels of use. Perhaps capacity, or tax/interest rates, or whatever else.
Now, you have your criminals who want dat money. So, you give them an item. A drill, specifically. Then, the criminals could walk into the bank, and using similar code to mining, and fishing, the drill would collect a resource "Stolen money" from the vault brick. After enough stolen money units are collected, they turn into a money bag item, which would then be worn on your bank. Each player could only have 1 money bag at a time. Now, the stolen money units collected could be directly stolen from the economy percentage, meaning someone robbing a bank successfully is BAD for the law abiding people, and the economy itself.
Now, with the money bag item, you also have 2 more function bricks, like the ATM and similar bricks which you stand on to activate. 1 of them is a Safehouse brick, and the other is an Evidence brick. Each being very restricted in their placement. If you have a money bag, and you make it to your safehouse brick, that stolen money is then added to the players money or bank account or whatever, and they have successfully robbed the place and gotten away with it. Now, if a policeman kills or jails a criminal and takes his money bag, he can take it to an evidence brick, they return that money in full to the economy, and are rewarded a smaller amount themselves. The amounts given to the player from these 2 bricks would be up to the host, to balance things for the effort required.
So already you have incentive on all sides. Criminals target banks, cops protect them, and players who build banks have to take security into heavy consideration. If criminals are allowed to rob banks, the economy goes down and law abiding citizens suffer. If criminals succeed, obviously they become rich. Players who build their own banks have a larger responsibility to make their banks less vulnerable, and maybe even have players guard their vaults for them. After all, there IS incentive for it.
Now, to add to the idea, how do the cops know a bank is being robbed? You could make a simply system for that. Vault bricks would need a name added to them, and they could be named based on the bank's title, or the location. For example, "Main Street Bank". Now, when a criminal drills the vault, that could then send a client message out to all of the cops on the server saying that Main Street Bank is being robbed. Then the cops would respond accordingly.
Now, all of that in place, just picture it. A small group of people get together, organize, buy a vehicle with lots of seats, and rush in. Some people drill while some stand guard watching for police. When the people drilling get their bags, they trade places. Now you've got 4 people who have taken a large chunk from the economy, and all of the police show up from all sides of the map to try and stop them. The criminals then have to get to their getaway vehicle, killing any police in the way, and drive back to their base to count their loot. Or, alternate outcome, the cops are organized enough that they meet the criminals quickly enough, with enough force, to take the criminals down, and return the money to the economy, making them the heroes of the day. I think, that would be pretty badass.