Basically, we need to move away from buildings that conjure resources. It needs to be about converting 1 resource to another. Food was chosen because you are seeded with a fertile land nearby as well as a gold deposit.
If you have a resource that doesn't have some cost associated with it, what happens is that the route to victory becomes about creating as many cities as possible without regard to any strategic placement or consideration.
I love this post, I hate the merchant.
If you really want to solve city spam, how about not putting in mechanics that necessitate it? You want to know why I spam cities left and right in my games? It's real simple, I have to.
Resources are spread all over creation, so we have to build cities all over creation to utilize them.
Work is the one and only universal input into the creation of any good or service. As food is limited, population should be as well. It isn't. Cities don't consume any food until after you build housing to expand them, so level 1 is food free.
Prestige growth controlled cities are, generally speaking, really bloody slow growing. It's nice getting access to the higher level structures and whatnot, but I can end a medium map against ridiculous ai, without bum rushing them, making champion channeler stacks, summoning elementals, or any other cheesy homo tactic I've found, long before I ever pass level 4. I have to do something with the 15+ excess food I can't possibly use because it's doing dick to advance my population growth.
Influence spheres also grow nice and slow. I can absorb and connect up far flung resources over the next 200 turns, or I can just pop down new cities right bleeding next to each other.
The biggest hose job of them all? Trade routes.
Real great that, instead of a nice, demand driven supply system of actual resources from production to refinement, I got this whore factory for food production. How do I make my 15+ food I can't possible use? Real easy. I just build a few other cities and run trade routes from all of them to the place with a farm.
Merchants don't make free money, but they don't consume food. They're specialization of the workforce, easing market access to the producers by functioning as middlemen to the consumers. They sell food, and any other product people would produce for sale. A trading market should thrive off trade and commerce, being of variable benefit in conjunction with the amount of production the city has. Of course, we got stuck with generic "materials" after all those wonderful posts about our in depth economy, so...
Abstractions are necessary evils only when necessary, any other time they're just a mess to clean up after. This is just one of the many messes. Spending 15 turns to create an "untrained" squad of peasants is another caused by not being able to produce swords and armor. Remember all those wonderful posts you wrote about supplying them with arms and whatnot to get an end result on the time it would take to get them ready? Beautiful memories, but they cause painful reactions.