> Romans only really cared about Italy

Yeah, so they famously instituted for-profit tax collection: "we'll auction off the right to collect what you can!" Are you telling me that the competing individuals who were willing to bid the highest amount for this privilege were less effective at it than the kings who had preceded them?

Historians often talk about Rome's "tenacity" -- the fraction of their male population they were willing to throw into the meat grinder of a failing war machine, the number of people they were willing to nail to trees when they risked their lives to complain about taxes, the lengths they were willing to go to in order to put down a tax rebellion (see: the giant earthen ramp up the walls of Masada) and so on. Rome is often credited with being more tenacious than their adversaries.

It's not impossible that taxes were generally lower, but I tend to suspect there are some serious qualifiers, like "in Italy," or "during peacetime," or "for those who the Romans were trying to make a positive example of."