I've had a detective agency since 1998. If you give me your name and recent address, for less than $50 I can get your address history, relatives, their addresses, neighbors, civil history, some criminal history, motor vehicle ownership (in some states), if you have a pilots lic, fishing lic, hunting lic, property ownership, history of the home and it's values, arial photos, tax history, and most phone numbers. To do this I have to say I have a legitimate reason. I only do it for attorneys, my policy, plus I don't want any risks. But if I can do all that, think what the government can do.
This morning I watched my wife drive through a neighboring town on a live traffic camera. Later while checking my bank account, I saw she had just had lunch in a local diner and what it cost her. (No I'm not stalking my wife. I was checking traffic for her on her way to work and was on the phone with her.
As far as your cell phone, you can delete all you want, but the police can still get it. I just had a murder case working for the defense and had to read 100 pages of text messages between the client and his friends. The client kept saying "I deleted all those????" ooops on him.
Big brother has been here. The only thing slowing them down is each police department, and all the federal agencies don't want to share with each other, afraid they will loose power and funding.