Aunt Kelly, the laws vary by state.
In Washington state anyone can take your pictures in public. You are not guaranteed any more privacy in public than being in public affords you.
The state's voyeurism laws only protect people who are in a place where they "would have a reasonable expectation of privacy"
In fact up until maybe 10 years ago it was perfectly legal to take "upskirt" photos of GG's without their knowledge or consent in a public place in Wa.