This is just such a fundamental misunderstanding of how the world works. Land doesn't pay tax. People do. And they pay it out of the things that they produce. Planting trees or painting crosswalks doesn't increase their productivity and therefore does not grow the tax base. Increased property values simply represent an increase in the tax rate. You can get this same "return" by cutting out the beautification and simply raising the millage.

Sure, if you make your city more attractive rich people from other areas may move there. But nationally that is a zero sum game. If a rich person moving to the beautified city from an ugly one the net change is 0 as the ugly city loses as much as the rich one gains. The only way for cities to actually get richer is to increase the productivity of their citizens. This means spending on education, infrastructure, and public health.