From a manufactureing stand point its not stupid
For them to put manual transmission in vehicles it can take 2-3 weeks, if not longer to modify the assembly line to install a manual transmission
Thats 2-3 weeks of people with out jobs, others being paid to change assembly line parts, countless hours of engineering not only going into the truck design to accept a manual or auto, but engineering the line, engineering goes into the actual assembly process and even industrial engineers to do all of the scheduling for all of this to sell a very minor amount of trucks with manuals compared to the market of automatic trucks
Would you rather pay the amish minimum wage to build your barn or pay an engineer to completly design it and just have the other guys build it anyway? lol