http://www.utraderobo.com/methodology.html
We aim to minimize WHT for our investors by examining the ETF strategy (asset class and domicile of underlying securities), its domicile and listing venue, as well as assuming that the investor is Singapore-domiciled in order to determine the applicable tax rates and double tax treaties. As a result, we have geared our selections towards London-listed, Ireland-domiciled ETFs which are not subject to withholding tax at the investor level.
However, heres what stashaway has to say
https://www.stashaway.sg/r/etf-taxes-returns-and-tracking-errors
It is normal for London listed ETFs
for S&P500 to have a greater tracking error. The biggest cause is simply due to London Stock Exchange not being in operation at exactly the same time as any of the US stock exchanges.
However, if you are buying and holding, why should tracking errors matter if it does not result in underperformance. Note: they are not claiming that US listed S&P 500 ETFs
peform better , instead they are making a fuss over tracking errors. Such tracking errors only kick in when you keep trading.
Same goes for the bid-ask spread. Sure, US listed ETFs are hugely liquid with small bid-ask spreads, better than London listed S&P500s (I ain't carring about those listed on other European exchanges). Again, if you aren't constantly trading, why should that matter?
Yet another point for people who buy ETFs on their own: you are subject to US estate taxes when buying US listed ETFs, and the bar is low at $60,000 for non resident aliens.
Part of the reason why 15% less withholding makes a smaller impact at the present moment is due to the current trend of US companies not issuing dividends and instead engage in sharebuy backs instead. This can change in the future.
Finally, if you are buying an ETF that track a world stock index, there is no way to have 0.0% tracking errors, because there is no stock exchange that operates 24 hours a day.