Thing is, Austerity breaks the flow of the economy as the populace are less willing to spend or lose power to do so.
Investment is important to get the economy flowing, but it needs to be done in such a way that there are returns in the future, even if the returns come from elsewhere in the economy (investment in a railway may give returns from increased industrial productivity and commerce, and not necessarily from sales of rail tickets).
Tax is fundamental because that's where the state gets its money. No tax, no treasury. Unless the state becomes the economy itself/the economy becomes the state itself.
From my experience Right Wing politics fails to look at the big picture, cutting spending on fundamental infrastructure and services, eventually crippling the economy. Left Wing politics fails to do spending strategically, doing so for "the will of the people", being specially prone to white elephants built under debt that may not be payable, eventually throwing the country into bankruptcy.
In just 25 years of life I've seen the two aspects in action. And the railways were the main victim of these swings of political incompetence.
