Good catch, Mike; I heavily researched these a few years ago, and made a few.
The one flaw in everyone's logic?
They are lowering a 4" dia bucket down a 6" dia pipe.
That pipe is likely to have an existing well pipe in place already, if you are on shank's mare going x-country.
The bucket you make - and carry - can't be more than 1.5" dia to lower alongside the existing pipe!!