The same umbrella can be shelter for one person and an obstacle to the person walking behind.

The same object is protection from one angle and an obstruction from another, and neither person is wrong about their experience of it. The person underneath feels only the shelter; the person behind feels only the edge at eye level. Position determines what a thing is.

Assume, then, that things you use without a thought have another side facing someone else. The way you take up space, the volume of your music, the timing of your requests. It costs very little to check occasionally: a glance behind you, a question about whether this works for the other person, an adjustment made before being asked.