The friend of my friend is my....?

I got reminded tonight that I'm different.
Because you know, I needed another reminder :)

I talked to a friend of mine today who works with Jack. She's a rope Top, really awesome gal who did my henna for DragonCon. We were talking about playing, and the lack of good opportunities to play in the town where we live.
So I suggested she come with me to Atlanta one weekend, perhaps October's FemDom and TNG events. She liked the idea, and I suggested that we could probably stay with Kat. I texted Kat, asking his thoughts on the idea of a FemDom friend of mine coming up with me and attending the events, and that she'd need to stay with us and liked the idea of coTopping him with me.
His response surprised me, that he'd have to meet her first.

I guess I forgot that open hospitality isn't second-nature to everyone. That a friend of a friend doesn't automatically get a certain level of consideration/clearance for most people.
I suppose I'm just very European about that- it's relatively standard practice in large parts of Europe that a friend of a friend is always welcome as a guest, and that if you know one person in Europe you need never stay in a hotel no matter where you go (of course, a certain level of consideration and respect is expected of the guest!).

Maybe it's being Southern. I learned it, I think, from my parents. They both had a lot of faults, I'll be the first to say- but one thing they always shared was an open-hearted hospitality and generosity that epitomizes, to me, Southern hospitality.
Even my aunts, whom I detest as a general rule, follow this Southern hospitality. One of them allowed my father to bring 5 friends- none of whom she had ever met!- from another state in to stay at her house during a week-long workshop they were all attending.

Either of my parents would bend over backwards for any one of their friends, and they expected (and usually received) the same in return. And a friend of a friend was treated as a friend in their own right until/unless the proved otherwise. I remember being 15, and a friend from Ireland who worked with my father had friends come to visit him in the States from Germany. C, our friend, didn't have room for the couple to stay, so my father immediately offered our house. They were friends of C's, and they needed a place to stay, so of course we would offer. The fact that I was taking German and could speak enough to help us all get along was simply a bonus. :)
That was simply how things worked.

To me, it's still how things work. A friend of my friend is a friend until they prove otherwise. It's how I've met the majority of my friends (it's how I met Jack, and A, for example). Sure, it's back-fired a few times, but it's been very successful far more times than it's failed me.

I asked Jack about it, and he suggested that perhaps it's our culture of fear. He has a point, someone we don't know ourselves is still an unknown quantity to some extent... but if I can't trust my friends to have good judgement about their friends, what does that say about me?

I'd really love to get some comments and thoughts on this. Im honestly floored by it. I don't blame Kat, and I'm certainly not angry or upset, I'm just honestly confused.