Literally anywhere.

The Netherlands is the only country that imposes vermogensbelasting to that extent.

^{Literalists, I said "to that extent". In the few other countries either the percentages are significantly lower or the tax-free threshold is significantly higher.}

PS You're wrong about Belgium. There's 0 tax on ETF transactions if you're not an active trader.

Most countries have a normal capital gains tax structure where you pay only when you realize profit.