The reason Eaton gear (the tranny company) isn’t doing so bad is that they are selling a sh*tload of upgrades for your typical 9spd manual tranny’s to turn them into 13spd semi-auto tranny’s ... increases fuel economy by about 0.4mpg (5% or so) ...
They make a “convertible”. It comes as a 9 speed spec’d for company fleets. Then when the trucks is ready to be remarketed to Owner Operators, they convert it to the 13 spd. O/O’s just like more gears :-)