In Australia and New Zealand we also have a GST system just like Canada. And Simgapore.
It's what a sensible country does. Your state based tax system is pretty brain damaged and only going to cause more and more problems as time goes on..... goodluck with that.
State taxes (or provincial ones in Canada) are bad enough but manageable due to limited numbers, and you usually know if you're in one state/province or another.
But the US goes even further and has county/district sales and use taxes, adding thousands of slightly different tax rates across the country. Check out California's... and that's just for locations starting with "A"! Texas has an an equally ridiculous long list of slightly different rates.
This means that the shop down the street, but in a different county, may charge you slightly more or less for a product that has the same sticker price (which are almost always pre-tax numbers in the US... Canada does too but at least we don't do local sales taxes). I suppose locals know exactly where the county lines are, but what a mess to keep track of.
I get the historical reasons why this is--it's similar to why there's no federal or even in-state standards for election systems. Each county is theoretically independently managed and sets their own rates. This works for property taxes and infrequent purchases, but not online goods and services.
It's no wonder US online retailers and services have resisted sales tax for so long, it's a logistical nightmare to set up the database of thousands of tax rates across the country and keep them up to date.