And not to forget the good old fashioned Phonebook that is still published in many areas, as well as City Directories that many cities publish. Lots of valuable information both Publications.Freaky to you (and her) but just business.
*-Emphasis mine...Was she born? (Yeah, I know, silly question, but it's pertinent, trust me.) If so, the state/country where she was born will have a record of that, with the full name, and most of them are now digitized and online for genealogy research, so getting her full legal name is not that hard to do. Did she go to school? College? All of that history is available through public records. Add in your marriage registration, her driver's license, voter registration*, real estate transactions (buy/sell/pay real estate or personal property taxes), credit applications (Mortgage, car, credit card) etc., and it's easy to put you and her together. Now add in an Android phone reporting everything done on it and Google has all it needs to make a list with her full name, phone number, address, family, etc., for sale to whomever has the money to buy it. Along comes a health care company who also knows she is a patient with Dr. X, is of an age to get close to Medicare, may be on AARPs radar as well, and you have the text to that number, hoping it's her. If it isn't, they have no real loss. If it is, they *might* win if she buys insurance from them. The wins are just frequent enough to pay for all of the misses, so it's a good business move. Freaky to you (and her) but just business.