The reality is that it simply doesn't work like that and there are so many reasons but I'll rush through some of the common ones. Venues vary insanely, no two venues are alike and I can assure you that if we could get 5 venues around the country that were the same oh boy would that make my life a lot easier (and probably a lot more boring too). They all have different setups, rules of what we can and can't do, when they open, close, certain things they can do awesomely, different rates, just that alone should explain enough.

There are differences in the crowds, numbers being the obvious ones but the crowds in terms of musical tastes, preferences, fashion, energy, socialising are dramatically different depending on the city. It's not simply a case of the cosplay/anime scene being the same nationwide plus throw in the complexity of how different scenes see Neko in different cities. In one city, the rave scene and Neko Nation goes hand in hand, in another city, the rave scene won't touch our event.
Staffing plays a huge role, certain things happen because of special people, depending on the cities, we've seen Touhou, Moe Swag, Vocaloid, MLP, industrial, hardstyle musically. Certain things happen in certain cities because of the people who have worked for something for that show and some things aren't feasible to travel and post around (no matter how many times you ask, we can't put bacon cheeseburger sushi in the post). Plus it goes onto logistics, I can do more shows in Perth because it's closer and nearer, Brisbane is far away and harder as an example, it can also work in reverse, S3RL will appear more in his hometown Brisbane than elsewhere. Then yeah, budget, more people = more money to spend on the show. Certain cities get more frequent shows and bigger shows simply because the budget is there, it's simple supply and demand. At the moment Sydney averages ten times as many people as Melbourne at shows and this isn't an exaggeration!

I'll touch on the S3RL issue a lot because this is something that always get asked all the time when is S3RL coming to *insert home city here*. It depends on a whole bunch of factors as mentioned above, Perth, there will be a return in the near future if all goes to plan. Adelaide, originally was part of our AVCon plan but that ended up falling through this year, once Adelaide gets bigger I'll be able to look into it again.
So yeah, this is something I could really go on with in terms of all the minor details, I should also mention that a lot of it simply comes down to my team that I work with, there is no competition between cities and the managers who run each city, they are aware of what happens in the other cities and keep an eye on the ideas that all the other cities do but at the end of the day we're all working by deciding what works and is relevant for each scenario, show and city.