I suspect most people are saying you're unreasonable OP because they don't have parents like yours, and don't understand what it feels like.
I don't either, but DP did, and when I first met her I didn't understand why she withheld so much information from them and seemed to get so annoyed about perfectly ordinary questions like "Oh who'd you go there with?"
And then I met them and found out that they had absolutely no boundaries around their daughter's privacy.
A simple conversation like:
"Hi, missed your call earlier so thought I'd ring you back"
"No problem, where were you, anywhere fun?"
"Nothing exciting, just the doctors"
Now at this point, if it was a conversation I was having with my Mum, she'd just say something like "Hope everything's ok" , leaving me the option to elaborate or say "Yeah all fine" and change the subject. Or if she did push for more information, I'd be able to say "None of your bloody business" in a jokey voice, and she'd get the point that she'd overstepped, without getting offended etc.
Whereas if this conversation was between DP and her Mum, then the next 15 minutes would be taken up with wheedling and pleading until either DP got angry and hung up, or she relented and told her Mum all about the infected boil on her vulva.
And it wasn't just doctors, it was everything. Where she was, who she was with etc. Her mum needed to know everything, and any bit of information that she told her Dad got passed on to her Mum, who then needed the full story.
At that point questions like "Where are you going" or "Who were you with" stop being pleasantries, or conversation starters. They're the beginning of interrogations, and you feel the need to shut them down, to lie about even the littlest things, and it seeps into your relationships with other people too.
DPs Mum died about 10 years ago, her relationship with her Dad is much better now, and she shares things with him and other people much more freely now. But I still notice her tense up every so often when someone asks something as innocuous as "Done anything fun today?"