I seem to remember videos of being able to change the zoom of the map by using two fingers like on smart phones. Every time I do this whichever finger the display senses to have touched the screen first moves the map display in that direction, without changing the zoom level. Is there a setting to turn this on? The only way I can change the scale is by pressing the + or - buttons on the screen.
I don't know whether this answers your question, but in one of the YouTube videos, they said that pinch-to-zoom only works when the car is not moving. Undoubtedly the theory is that pinch-to-zoom is too distracting.
Actually, pinch to zoom does not work at all in 3d mode, only 2d mode. I usually keep my map in 3d mode because I like it. Touching the map re-centers it. You need to use the (+) and (-) buttons to change the scale.