a straight block freewheel or cassette has cogs increasing in size by 1 tooth at a time. a straight line.
going lower the diameters increase in a parabolic curve, to have each gap bigger than the last

IGH have been engineered to increase as a % over the next smallest gear ratio,
so difference is less, closer together as you shift downward..

Basic Math is a weak subject, these days, it seems.