James May calls this "Christian motoring". Golden Rule etc

While leaving space is nice, the person on the highway already typically has right-of-way.

It's really not. I drive at an upper-percentile pace, so I am rarely dawdling along in the right lane.

However, on the rare occasion I've found myself going slowly in the right lane, it's stunning how incompetent most people are at merging. It's like they don't even consider looking for an opening in traffic, matching the freeway speed, etc. They just lumber in front of you at 43mph, and maybe, if you're lucky, look in their mirrors after they've already caused you to slow for them.