If they can't keep a cache of your recent locations, it would be difficult for them to apply optimization of your location, prediction of your car's path, etc. and Google Maps would be a much more jarring experience, akin to a GPS device. I think they do need the client to send recent locations per request if they want to deliver an optimal experience.
For example, what if I wanted to implement loading automatic nearby locations? Naively, I could fetch the results within a radius R of the current received location. However, that's not good if I'm on the highway. The smarter algorithm would take into account the car's position, velocity, and angular velocity to calculate a better spot to query around, or perhaps a different shape to query in other than a circle with radius R.
Nobody wants to use a maps app that feel like it's from 2004. There's a reason people put up with giving their data away -- because data drives machine intelligence, which makes your maps app smoother, more responsive, more useful, and overall a much better experience.
I, too, don't want to give my data away. But when I'm in my car, the most important thing is that I get to my destination safely and on time. That acute need vastly outweighs my own philosophy on who I think should have my data.
I'm just being honest with myself. I can't deny that I make heavy use of products that make heavy use of my personal data. People in this community seem to think of personal data collection as a form of parasitism, but in reality, it is far closer to mutualism.
Or you can use the Navigator app by someone else, that has a free option, nothing feeds to the Google monster, and behaves pretty much exactly like an old style GPS device with some modern additions.
For example, what if I wanted to implement loading automatic nearby locations? Naively, I could fetch the results within a radius R of the current received location. However, that's not good if I'm on the highway. The smarter algorithm would take into account the car's position, velocity, and angular velocity to calculate a better spot to query around, or perhaps a different shape to query in other than a circle with radius R.