What feels obvious to you may be invisible to someone standing inside a different history.

What seems self-evident to you was assembled out of your particular history, and someone with a different history may genuinely not see it, without any failure on their part. The frustration of explaining something obvious usually means the obviousness itself is what needs examining.

When someone cannot see what is plain to you, ask what they would have to have lived to find it plain. Then explain from there, or accept that they may never quite arrive.