Google maps, Waze and Apple map all give the road distance both initially and after you select directions. None of the give line-of-sight distance
Actually I was surprised by this as well but he's right.
Open Google Maps and try a "search" for say "supercharger near by"
For me it shows one at 13 miles. Then I click it and choose "Start" it changes to 18 miles.
Perhaps if you leave the search list up long enough or click on an entry and leave it up it might refine the distances in the background.
The list is just a guide for what's closest but be sure to double check actual distance once you start navigation to it. Sometimes as the crow flies might be close.
I've always noticed this difference and always thought because it wasn't using an accurate fix yet. I never considered it was showing as the crow flies initially. I didn't check the other nav apps.