Yep this happened to me yesterday. In a taxi, the driver was following Google Maps, which showed a 22 min ETA, with one or two alternatives adding a minute or so. My phone was open and showed the same options. He felt certain that he knew a better route—via a highway, not a back road—and when he took that first rogue turn, Google Maps adjusted and the ETA instantly dropped to 14 min.
Google's doing it to balance traffic loads. Remember that you're the product, not the customer. Right now it's just in the testing phase, but soon the capability will be sold to municipalities and billboard owners.
I'm not really sure where I sit on this, but I have to admit it's a hell of a capability. There's some big implications of this degree of control over a population.
are you saying it has a stake in roadway advertisements and prioritizes routes that maximize billboard views per trip? That’s pretty depressing :/ yet also capitalism I guess