Very briefly, I can say that I'm not convinced that it's a good idea to leave that trail and that there are more concerns about it, especially as you combine databases. It's possible you can cross-reference your calling records with your movements that day with all sorts of things, and I think there are more implications to this that can be bad in certain situations than we're thinking about.
As far as using cash is concerned, you can't use cash over the Internet and you can't use cash in a lot of businesses—they want to take a credit card—so you're leaving a trail there.
I don't know if that answers your question.