You'd have to sit there for 8 minutes converting all of the "measurements", figure out how much is in each package, and then only after doing it for all rolls and brands, you'll be able to compare.
Easy math, but takes time. No one said it's hard. It's just time consuming.
There is no standard roll of toilet paper so it's impossible to compare that way between brands. That's why everyone says to look at how many square feet are in the package.