There is just one way to understand another human being: shared experience. The more extensive your experience is, the more people you have around to share something with - and the fewer to share much, not to say all of it. Every time, by taking (or refraining from) a new step you choose between experience and understanding - the 'time vs money' of the mobile world. Every time opting for a new experience you pay by proportionally decreasing the range of what you have in common with the other human being(s) by your side. To paraphrase, the more you have got to share, the thinner the circle to share the whole of it with.

A way to maintain this vital resource is to stay as local as you can, with as much experience being shared by lifelong neighbours as possible, preferably for generations. Whether you leave the neighbourhood, or the neighbourhood dissolves into something new, shrinking of the common base for understanding will hurt the unprepared badly. That's how fundamentalist anxiety comes into being.

By preparedness I mean a) taking cultures as a market to shop from rather than a temple to worship in, and b) replacing one solid lifelong understanding among a very limited number of people by a flexible and fluid configuration of short-living, 'situational understandings' based on shared experiences of a smaller scale. On the bright side: these are to be shared within a much greater group of people, the humankind is the limit.

What happens when two or more people go beyond a shared experience, thus - beyond understanding. Scenarios vary: some take (pointless) efforts to explain things that could only be gained through experience, others cut the cost by withdrawing and/or making a note in the 'take as is' section of their mental organizers. I, for one, apply the principle 'judging me - yes, mentoring me - no', which has saved me a lot of time and effort.