You're referring to an OBDII scanner, right? No dealer should be using one of those- all diagnostics should be done with SnapOn, Sun or laptop with software- if they're using the laptop, they would be using Rinda or some other software that allows recalibration 'on the fly' with some vehicles. I have a scanner and it lets me see a lot, but it doesn't let me do as much as the SnapOn. OTOH, it was $65, so I don't expect it to do everything.
I know some cars/trucks can receive a different 'chip', but the marine have sealed ECM and diagnostics & recal are done with the laptop connected- first step after connection: check for codes and if possible, run the boat on the water to acquire data, shut off the engine/turn key to ON, load and save the new config file, close and run the engine with the boat on the water, checking performance. Takes less than five minutes.
EVs are compounding the issue, but another problem is the lack of people who want to be mechanics. The high school I attended eliminated its shop department in the '80s and I think that was a gigantic mistake, but if nobody wants to take the classes, what's the point? Now, they want to improve the department in whatever form it has taken, but a lot of the emphasis has to do with Robotics- they call it the STEM Department. The local Technical College has just about all of the equipment and facilities that would be needed to teach people what we had when I was in high school, but that leaves students 1-4 years behind where we were- after HS, someone who had taken enough shop classes could have walked into a good job without needing to be trained from the ground up and now, that's rare although a high school not far from here has an auto repair program that competes against other schools and is a perennial winner. We need more of that but I seriously doubt my high school has as many gearheads as we did when I was there and we had real 'greasers'.