"On the basis of what your comment, the US should cut all taxes because they are all waste."

Nope, I didn't express a conviction that this is a linear function from 0 to 100. My statement should rather read as "If, at current, the American public sector is unable to provide good roads and sidewalks while redistributing 40 per cent of the domestic GDP, I find it hard to believe that the situation would improve much if it redistributed 45 per cent instead."

Good roads and sidewalks aren't that expensive. The Romans and the Incas could maintain them with a more primitive economy, and a well-run modern city should have no old potholes anywhere.