I'm sure this has been suggested before, but I will create this suggestion anyway.
I think the Tax collector setting should be able to go hire than 30,000 of each resource. If I am able to build 10 Level 5 strongboxes and have a storehouse...I can now hold 280,000 of each resource. If I want to use the tax collector setting, the maximum I can set it for is 30,000 and therefore my storage is going to waste. So I think you need to increase the limit dramatically.