For me it means ...
What I tried to say:
You are used to kissing and to let people very near (I mean literally the space, the centimeters ...) from being a child on. You learned it this way and so you are famliar with it and you like it. Because you are famliar.
I learned that kissing someone has a completely different meaning. I learned to feel comfortable with another distance when greeting someone. So I am familiar with an like this different custom. And because of having experienced this all my life, I know how to judge it. I am able to feel the warm relation in it and I can easily get to someone even not coming him or her near in centimeters.
Same with "Sie" and "Du". I know this from being a child. And it doesn't hinder anything when meeting another person. I just know how to deal with it without thinking about I. I can feel the other person right through.
But: I can not "feel" the other person when he or she comes near like when kissing for greeting or when using "du/tu ..." I have to remember myself: This is not a friend who is near. This is just someone I just met. Behaving like a dear friend is just a custom in this country. ....
note: In northern Germany there often is no "Sie" but just the "Du" like in Scandinavia.
In the Netherlands (u) or France (vous) there is the equivalent "Sie" at least for strangers. And in the US I experienced with "Sir" something we have no real expression for in German. (I think.)
It's all just about what we know in a deep sense and what we are used to.
Endo sensei last week called exactly this our jail/prison. ;-)