No, IANA Economist, but I'd wager that states in the US are much more homogeneous than are countries in the EU, both in terms of laws + regulations and in labor productivity. Plus, there is a (more or less) democratically elected government that is (nominally) responsive to all of its citizens. Much more so than the various EU branches are, at least.

Not true. There are a number of important differences. The US gradually merged into a single currency over a long period of time. As a nation the states have a sufficiently integrated fiscal policy such that budget redistribution is possible. Furthermore the US has a common language and genuinely frictionless trade between states developed over many years. The Eurozone is a bunch of homogeneous economies glued together without fiscal integration or adequate redistribution mechanisms.

The US has federal taxes and mechanisms to redistribute money from richer states to the poorer states to address this sort of imbalance.

While there are no EU direct taxes, there are redistribution schemes in the EU. I don't know how their magnitude compares to that of American interstate redistribution though.

I'd argue that taxing the rich more and funding non-broken-window public infrastructure is a better policy for growth.

Including investment in education, transport of all kinds, 'going green' (maybe even large new-generation clean-nukes), and also dangling carrots in front of RnD / upgrades likely to produce positive economic impacts.

Not mentioned, since the focus on European governments probably means universal healthcare, is universal healthcare as public infrastructure. That too would be a useful structural improvement and serve to reduce economic friction while improving worker productivity.

No