The only difference is that the VAT is a certain % depending on your country (mostly 15-25%), making it easy for a merchant to calculate it with a single data point. Percentage is also always a fixed round number, so you can calculate it in your head when you stumble upon "+ VAT" somewhere without providing that data point to the merchant for calculation purposes.
I used to live in Turkey, where taxes on some stuff are insane but most people won't ever know because it is not as obvious. In a similar vein, income tax is also quite hidden in Turkey, at least from yhe perspective of employee
My favorite example of how absurd it can get in the US: one side of my friend's street has 9.5% sales tax, the other side has 7.25%. same state, city, and zip.
All hospitality prices must include cleaning and service fees.
It is only the US were hidden fees and charges may apply and the price regulation, if any, is more tilted towards corporations.
Only upfront shipping charge is tricky because it depends on so many factors.