Actually there is another point here which you have missed. It is nothing to do with Zurich's infrastructure but to do with the tax system... Because Zurich has a large (Swiss relative) GDP they need to directly subsidise the "poorer" cantons tax- This means that if Zurich did not have this weight on its shoulders the tax would be much lower. Interestingly they have broke the tax rules for the maximum two consecutive years and next year, at least in theory, they are obliged to substantially increase taxes. It will be interesting to see what pans out!!!