I don’t agree with the person you replied to but the answer to your question is:

Because the US collects taxes very differently, so you can never make a fair comparison between identical tax categories.

Just look at the gasoline tax differences between the two. The core purpose of that tax and what it’s used to fund varies dramatically between the two regions. So, naturally the amount being taxed would be different.

Also, The US govt tends to have taxes below the rates needed to operate (US has a higher deficit), so the taxes will more likely be lower by comparison.