I love it when someone come on the bus and has heavy things on them and they realize that the bus seats are all taken, or even some free where the person didn't put a bag there, they go stand in the wheelchair and luggage section, EVEN THOUGH there are spare seats to use.

Well, some years ago I had severe problems with my back, and I couldn't sit, I had to stand.

By now I can sit, but I don't mind standing. If I'm going a short distance, I will most likely stand even if there are plenty of free seats. I do mind that there is too little space for standing on our public transport, particularly our local trains.

But yes, the one-empty-seat-between-each-person is real. I used to be annoyed with it in my childhood and youth (like, if travelling with my mother, there would usually be no free double-seat for us, only single seats). Today, I mostly go with the flow - but when/if the transport is starting to get full, I do tend to pick up my bag from the neighbour seat and put it on my lap, or move from the outer to the middle seat.