If you don't know math, then yes. Most people don't know or care that "adding 5% tax" is equivalent to multiplying by 1.05. They just know that you have to add 5% for tax. So 72 + 5% makes perfect sense; 72 * 1.05 is terribly confusing.
But that's why most people get stuck with percentages, even if you give them a calculator.
They can work out what 8% of 347 is. But ask them what 43 is as a percentage of 172 and they can't do it. Or if a widget costs £250 after a 20% discount, how much did it cost before -- they can't do it.
This actually puts these people at a disadvantage in real life. Just look at the arbitrary packaging sizes and how effective they are at fooling people into thinking they're cheaper or equally expensive just because they're unable to figure out that the "new packaging with 25% extra for free" is actually more expensive than the old packaging that contained a little bit less.
It is. It saves you from an extra mental operation. What's the price of that $56 shirt after 22% off? Doing 1-22/100 in your head adds an extra possibility for error.
Using a classic calculator (i.e. one that doesn't obey operator precedence and thus doesn't need parentheses) that's three operators (including "equals") and a total of 10 buttons to press.
56 - 22%
That's 6 buttons to press. Arguably, 6 is less than 10 [citation needed]. But I find it doubtful that this saves a noticeable amount of effort.
If you're multiplying by decimals, you already read "22%" as "0.22" and "-22%" as "(1 - 0.22)". There's no mental overhead in typing that unless you mean rote copying.
Maybe this is a matter of school system priorities. In my country children are introduced to percentages using cross-multiplication. They are also required to write the entire calculation process down in exams in order to pass (to make sure you actually understand the calculation and aren't just blindly entering numbers into a calculator).
