That's fair. The GPS nav does tend to eliminate obviously scammy behavior which historically has been a significant issue with cabs. (Never personally had an issue in Vegas but have elsewhere.) But it also eliminates local knowledge optimization as well.
I particularly remember taking a cab in Las Vegas many years ago trying to get from one end of the strip to the other. I was an obvious tourist - so he took the "faster router" around the city - just to "realise" that the exit he was going to take was blocked due to construction work and he now had to do a huge detour.