simcity-buildit – Where Do Gifts Appear in Neighboring Cities in SimCity BuildIt?

Here is what I received from EA:

Please note - the figure of 20% tax is calculated from levels and ratios for happiness and population, it's not as simple as happiness multiplied by population! A 20% tax rate is not simply 20% of your total population number in Simoleon form. If it were this simple an equation, early level Mayors would receive barely anything and find it a real struggle to make money for a long time, whereas higher level Mayors could buy everything in sight and would dominate the Markets. We didn't think this was very fair, particularly for a free-to-play game, and the balance of the game would have suffered too much.

The perk itself doesn't matter all too much since it unlocks buildings that will (as you mention) boost your population. I do find that you can get a bigger boost in comparison to land size taken to build a heliport instead of a university. It's a smaller building that gives the same boost to a smaller area, but easier to put into your infrastructure because it's the same size as a residential house whereas the university is oversized.

It does however unlock different hints, for example if the residential building is by an education building they'll say, "We live by smart sims".