Tax breaks can certainly be seen as a form of public investment. But the $22M figure for the Twitter tax break is a bit of a fantasy.
That was supposed to be a break on local payroll tax to the city of SF. Think about that.. I doubt any company in the history of SF has paid $22M in local payroll tax. That would be absurd. So where did the $22M figure come from?
Turns out there was a change passed a few years ago in between the dotcom booms that added stock option gains to the definition of "payroll". Since there were no startups happening at that time, nobody paid attention to this obscure change in local SF law. And it was never enforced and to my knowledge has no corollary in any startup-rich city. (Because it would be insane and drive out all startups.) So that's where someone came up with a "$22M" calculation.. by taxing the gains on early stage employee stock options. Even though the city bears no risk like early stage employees do.
If you were to just look at paycheck amounts as "payroll", Twitter's tax break would be valued at far less than that.
To be clear I don't think Twitter should have gotten a total tax holiday and anyone who thinks they would've moved to Brisbane is a fool. I think the city should have just un-done that dumb stock option tax.