That was your scenario about having a car on the rack needing a specialty to complete a job and needing your truck guy to rush over and deliver that specialty tool same day.
If you have the time to reach out to your truck guy and describe what unknown tool you need to finish the job you probably do need to pay extra for “service”
You could also spend those few minutes just looking up what you need and ordering it.
No, you took my scenario and then extrapolated to the Nth degree. You purposefully introduced the least likely scenario, then attempted to hold that up as the norm.
As for "just looking it up then ordering it," sure you can do that. You can look it up and give the tool truck guy the part number. But ordering it online and waiting for it (which is frequently a minimum of a few days out, even if you pay for overnight shipping), is not going to get the car off the rack today.
Further, there are lots of times when there is no "just looking it up." Frequently, it requires a bit of research. Frequently, it's not some specialty tool designed by the factory and given a part number in some manual, but a tool designed to make the job 10X easier, designed by some aftermarket tool company.
And that's not the only service. The mechanic might be looking for this or that tool, and there are multiple manufacturers who make it. Which one is the good one? There aren't a lot of online reviews from professional mechanics on such things. But I as the tool truck guy know the one made by X company works while the one made by Z company doesn't work, or breaks too easily, or whatever.
Again, you're welcome to shop the trucks right out of business. Go for it, I'm a writer now, not a truck guy. I don't care. But when you need the advice or the special service that used to be provided by the truck guys, they won't be there, just like the real hardware stores, electronics shops, building supply stores, etc, etc, etc, have all been replaced by the big box and online retailers.
Just like the real parts stores where you didn't need to tell the zit-faced kid behind the counter what hubcaps the car came with so he can get the correct wiper blades are gone.