Or the government could seek to learn who has been attending political protests or advocacy-group meetings, checking which phones were near a particular tower at a particular time. As the law now stands, authorities can often ask your cellphone provider to release the list of every cell tower your phone contacted without ever needing to go before a judge to get a warrant, which would otherwise require them to show probable cause that a crime has been committed.
There are those who see absolutely nothing wrong with the government being able to request, or even require, such cooperation. The phone was with you in public places. Anyone could have spotted you entering or leaving the doctor’s office or support group. And the records the government is requesting were maintained by a business for its own use. Hardly private, right?