The techs probably ment you were off by 2.5 degrees not inches. They dont know how to read their own machine!
If you were off 2.5 inches you would be shredding tires every month and it would mean you have bent a control arm and it would be noticable damage!
Shims are not a fun process, it can take several hours to get it right, its very nerve racking, and they simply dont want to mess with it.
Furthermore they will not have the shims on hand to do the job as they tend to be specific to each vehicle and passenger vehicles made after the mid 90's do not need them so the demand is low.
Any tech under the age of 30 probably doenst know how to do it anyways, or even know what you are talking about.
The shims come in sizes ranging from 0.5 to 4mm.
Furthermore, if you are thinking or doing a lift on the truck, or replacing the contol arms or ball joints in the near future, dont worry about it.