I often see people say that we don't have an expectation of privacy in public. However, it seems to me that ignores the nuance of actual social norms.

- Eavesdropping is generally considered anti-social.

- Taking up-skirt pictures in public is, I presume, illegal.

- If someone buys their prescriptions at a public grocery store, would it be alright for someone in the store to photograph their medical data?

It seems to me that the law needs to differentiate between the general sense in which one doesn't have privacy in public (e.g. the public probably has the right to know if a "family values" politician goes to a strip club) and actively spying on someone.

This is particularly the case when technology makes spying possible in a way that it wasn't previously. For example, I imagine it's not uncommon for many people to carry confidential information openly (say carrying a prescription in your hand as you walk to the grocery store) because it's not realistically possible for someone to read it and connect it to you. However, that changes with high speed photography, OCR, and facial recognition.