My daughter’s rescue pups have learned to share the couch. They could each take a side, but they prefer to share one end. They worked this out over time with a few growls, nips and tussles, but they found a solution that suited them both. We learn to share in much the same way.
Growing up my life offered many opportunities to learn to share besides formal school settings. In our first home five people shared one bathroom. Eventually we owned one television. I shared a room with my little brother for many years. When I rode the bus I shared my seat with whoever sat down next to me. I went off to college and shared my room with a stranger that I first met on the day we both arrived. After college I shared an apartment with a friend. By the time I married and had children the habit of sharing was well established.
I don’t think sharing comes naturally to children, but that is the best time to instill the habit. By the time we are adults, we ought to take other peoples’ needs into consideration at most times, whether on the road or in the grocery store. I wonder if some of the people around me demanding full attention despite other peoples’ existence never learned to share. Perhaps they had their own bathroom, their own room, and their own television. Perhaps they even got to dictate their choice of roommate.
I imagine many of us could benefit from remedial education in sharing. Unfortunately I suppose those who most need it would never sign up!