Plutocracy also gives a tourism boost, that could account for the difference

It looks like every one of my 21 planets was producing 158.90 from tourism before the government change... 0 afterwards. It doesn't matter if the planet was just settled last turn or was around since the start of the game. I'd like to know how this represents 1% of anything in my empire or what 1% tourism even means. It seems like a very insignificant stat to have such an overwhelming affect!

With Retribution (and the base game update released at the same time), tourism has been mitigated by not allowing a building to be placed on each planet, which I believe is a good fix.  As you can see, Plutocracy bypasses this tourism nerf.  I would suggest that the Plutocracy tourism income be dropped by an order of magnitude, down to 0.1% tourism income or something similar.  Again, this means that each planet acts as if it had a 1% tourism building on it (such as the Import-Export center).  Very overpowered.

Also you can eventually get up to 13k over time with the right influence buildings and starbases. Once I get interstellar plutocracy I never look back. It completely blows the trade bonuses of Objectivism out of the water.