All this seems like good old stereotyping to me. It often comes down to the individual family or even the individual person. Maybe their social skills, maybe their level of selfishness. Maybe also how much they care about how they're seen by others vs how comfortable they are being themselves. A lot of factors can play into this.
Treat everyone, no matter who they are, like someone you admire and you can’t go wrong anywhere in the world.
When you make a huge generalization like "the northern states I'm from primarily developed their culture from Scandinavia and Germany and tend to be more 'ask' than 'guess'", it's possible to immediately find tons of counterexamples. It tends to make people feel good to find flaws with generalizations, but they then argue too far the other way. "Since there are many counterexamples, your claim that the North is mostly 'ask' and the South is mostly 'guess' doesn't hold water."
But what exactly are they saying? The Northern US and the Southern US are exactly the same? There's no possible generalization to make about the cultures from either place?
Instead, at every possible delineation people have made in their counterarguments (poor vs. rich, urban vs. rural, man vs. woman), I find the same generalizations mostly apply. A poor northerner is likely more "ask" than a poor southerner, based on who I've met. Northern men are generally more "ask" than southern men. My wife's father is certainly less intensely curious about my needs than my own mother, but he's far, far more curious about my needs than my father, and almost every other northern father I've met. I've met a great many people, and lived all around the US, so I'm not just shooting from the hip here.
> she had been brought up to feel extreme insecurity
This reminds me of a quote from Buffett from about 40 years ago. He said something along the lines of "when women are raised, they hear and see a million reasons why they cannot do things whereas men see and hear a million reasons why they can do things". If I would be convinced by the world that I am not good, then sure I would treat guests amazingly well. If I would be convinced by the world I‘m amazing, then why bother treating guests well? They can say it if they need anything.
I‘m happy to hear counterarguments if you have them