There is a name for this kinds of services. It is called SPAM. Once they collect enough data on you they can sell the data to advertisers so they can send you "targeted advertising" which is the holy grail of the advertising industry and can make a lot of money for whoever can provide the targeting data. Worse than that, there is nothing stopping them from selling the data to companies that want to check up on you specifically.In order to better serve your communications needs and to identify, offer and provide products and services to meet your requirements...
I do not know how far they are actually willing and able to go, but here are some things that are technically possible:
Your phone is spotted at Supermarket A regularly. They can sell your data to Supermarket B and C so they can try and get you as a customers.
Your phone is spotted at coffee shops. Now, as you drive down the road you get a text every minute or two from coffee shops you are driving by.
You send texts to numbers in Europe. Your number is sold to airlines that fly to Europe.
You routinely drive over the speed limit (they know via GPS). Your number is sold to radar detector companies and lawyers specializing in speeding tickets.
Your car insurance company can buy data about your driving habits (speed, frequent lane changes, rapid acceleration, acceleration approaching intersections) so they can set your rates appropriately.
Maybe your health insurance company gives you a discount for belonging to a gym (mine does). Then they can buy the data to see if you actually show up there. While they are at it, they want to know if you hang out at bars.
You fly to some place and turn on your phone after landing. Before the airplane gets to the gate, you already have 10 spam texts from local hotels, eateries and escort services.
Since the permission does not specify what is out of bounds, they can even scan all your texts to get a better picture of what is going on in your life at the moment. Imagine that you get an alert that you have 4 texts. The first one is from your spouse, followed by 3 from local florists suggesting you send her flowers because she is mad at you! The technology is already there for it.