There's too much stigma around mental illnesses around neighborhoods near me, so I don't think I would give up info that I have a mental illness to a stranger.

Heck, my co-workers don't even know I have a mental illness, I am very selective who I tell. I did let some of my co-workers know I see a T as the reason why I come into work late sometimes (less stimga there as that is just "counseling"). Most were supportive of it, but a few looked down on me for it, so if people I know reacted that way to something lesser than mental illness, I would never disclose it to a stranger.

The only exception is if the stranger is professionally qualified to help me and I am talking to them in a professional setting. I.e. - my current pdoc and T were strangers to me when I first started seeing them, but I was open with my illness as dx by 1st pdoc with them as I was seeing them for help.