When it comes to empty buses and rail carriages, I wonder if etiquette varies around the world - i.e. in some cultures, it would be considered rude to sit next to someone on an otherwise empty carriage and the opposite in other cultures?
In the early 2010s, I did a lot of project work in London and often used to spend the working week there and travel by rail from my home in Manchester.
Due to the nature of the work, I could be very flexible with my hours and it was therefore often possible to get cheap rail tickets by travelling at quiet times - these cheap seats had a mandatory seat reservation and for some quirky reason, first class could often be cheaper than standard class.
I would sometimes travel to London on Sunday evening for an early start on Monday, work long hours and travel back north on late Friday morning.
I wasn't too bothered about first class, but if the price difference on the already cheap ticket wasn't too much, I would often use first class.
One Sunday, I was heading south - the first class carriage I was in was empty - I was sitting at my allotted seat - looking forwards on the single side of the aisle - i.e. not at a table of 4.
At Stoke on Trent, a giant of a man boarded the train and sat opposite me. I'm no midget at 5'10" but this man dwarfed me. I was immediately irritated but sensed a friendly demeanour so I stayed put, listening to music on my noise cancelling headphones. Unfortunately, for reasons I am not quite sure to this day - whether it was the sheer size of him or whether he had something else in mind, the man's shoe quickly made contact with my own footwear - just a slight contact, no harm done, especially as I was wearing safety boots needed for my job. A glare of irritation got an apologetic glance. A few minutes later and he repeated his movement. The glare morphed to a twisted snarl of rage - again, he's apologetic. When it happened again moments later, I got out of my seat and without a word, moved diagonally backwards - i.e. to the empty table of 4 behind me and glared at him. His face was pure resentment - he absolutely hated what I did.
Another time on the same project, going home this time on Friday morning. The Euston to Piccadilly train was very busy and I was thankful that I'd got any kind of seat, standard class this time, facing backwards, window airline style seat right next to the toilets - hardly the most desirable seat on the wee-reeking Pendolinos but it was fine for me. When I got to my seat, there was a teenage lad sitting in it, with his hissy headphones on full blast and with his gadget plugged into the all-important power socket. "I reserved that seat - please move", I said once I had his attention. Fatefully, he rolled his eyeballs at me. If he hadn't done that, I would have got the 4 bar extension lead out of my rucksack so he could share the socket. He grudgingly vacated the seat and sat in the aisle seat next to me. "Can I at least use the power socket?" (No 'please'). "You mean the power socket I reserved with my seat - that socket?", I sneered. He got up and found somewhere else to sit.