That's basically what I do. I have a spare phone with a pay as you go number that I give out and use for other services that want my number. It's basically a dedicated spam phone/number.
What I find funny are the people that accept it when it's a Western company doing it, but then freak out with it's a Chinese company doing it (especially when they don't even live in China).
> why do they need to know where I'm at after I get dropped off?
In China, there's a company that provides a free loyalty point program. The store signs up for it, and users download the app and can use it to collect points when a transaction is made at the store. The points can then be exchanged for discounts and other stuff.
All of this is free. How they make money is by selling the user behavior data.
One of the features is the app tracks where the user goes after a transaction is made, so stores can find patterns and possible ways to cross promote.
For example, it might show a trend that 60% of customers will go to the movie theater after dining at your restaurant. Or will go to the Nike store after visiting yours, so perhaps you want to adjust your prices, etc.