I disagree cafes have a rule that every unoccupied chair is 'public space'. If this was the case, there would be notices up, or staff would tell people to share tables. Can you imagine the look on a barista's face if you said 'I want to sit at that table because the seat looks free, but those people don't want me to join them' or 'that lady said the other seat's taken but I don't believe her, please tell her she must let me share her table, I don't like waiting or standing up.'
Of course there isn't a common rule about this! What this whole thread is about is the unwritten social conventions that people come to understand when using cafes/coffee shops. We disagree on what that unwritten convention actually is. However, there seems to be more people on this thread who disagree with you than agree with you. Who knows if that is representative of the population as a whole. My experience is different to yours. Maybe there are regional variations, perhaps London has a different social convention to other (less busy and crowded) places. I'm also puzzled by you assuming that these disagreements should be refereed by the staff in the cafe/coffee shop. They aren't there to sort out tables for customers, unlike in a restaurant or table service cafe. If someone said no when I asked to sit at the spare seat at their table, I would simply look for another table with space and not harrass the person who said no! I would privatey think that they were being somewhat selfish and rude, but again that's just my opinion.
IME people wait their turn rather than barge into someone else's space.
I don't think anyone has said they would barge into someone else's space. That would be rude. People have said they would ask if they could sit down, perhaps pointing out the lack of spare tables. They wouldn't then shuffle up to you, and start joining in your conversation!
I tried to imagine going up to one of these people and saying 'please move your laptop, tray and papers so I can sit down and share your table, as I don't like waiting'... I couldn't imagine myself (or anyone else) doing this in real-life. It would be incredibly rude and intrusive.
I wouldn't disturb anyone in that position, unless there really was no option and I wouldn't dream of doing so on one of those tiny tables. I might ask if I could use the spare chair just to sit down, and turn it away from the table. I might also ask if they could make a little room for me to put down my drink or plate. A cafe/coffee shop is a shared space, where tables are not booked out to a party (of one or however many). If you need to spread out and work, then a library would be more suitable, or a place where you can book a table. I think it is selfish and inconsiderate to go to a busy cafe/coffee shop and use a large table like that, for hours. If I had set myself up like that (say at a table for 4, on my own) and then the cafe became busier, I would tidy away a bit and offer the spare space to people looking for a seat. That's just a human kindness, as far as I can see.
But having a nice lunch in a cafe is not a situation where anyone should feel obliged to squash up with strangers or share their tiny table.
I agree. A nice cafe, with table service, and this would be weird. Sharing a tiny table which is really only meant for one (even if the cafe has wedged two chairs around it!) would be weird. A busy coffee shop with no space, and counter service, and it's not wrong to ask if you can sit at spare seats at the most under-occupied table. Of course if the person sat there tells you their companions are in the loo, or just coming from the queue or whatever then that's no problem. If they say no, with no reason given, again no problem but they are being unreasonable in that case, and selfish and inconsiderate. If the reason they say no is that they have issues around personal space, a fear of a particular gender, or social anxiety then they are being less unreasonable, but the person asking cannot possibly know that.
So it's appropriate to table-share in Costa, but not in say... Nandos or Wetherspoons... or an artisan cafe where waiter comes to table? How do you justify the different rule? Lunch prices are similar, people still want to have a nice meal or drink undisturbed.
Again, there's no rule... I was giving my opinion of the unwritten social conventions. I've explained why table service makes a difference, and it's down to the waiting staff needing to know which order goes to which table. They need to allocate people to tables, so who sits where is up to them. I don't know how Nandos or Wetherspoons work, having never been in either of them.
I used to work in a city centre, with a set time for lunch. You don't HAVE to choose a busy cafe, nor do you have to sit-in. If you can't plan ahead to avoid the busiest time, be prepared to take-out or wait for a table.
If you can't plan ahead to choose a table service cafe/coffee shop/restaurant then be prepared to be asked to share your table if it gets very busy. If you want more personal space than nearly everyone else would expect, then you need to organise it to suit you.
you will be surprised how patient the majority are and how much we respect each other's space
I respect other people's personal space, and I am extremely patient. However, I don't agree that your personal space extends to cover whatever size table you happen to sit at in the situation we are discussing. The tiny tables they have in coffee shops are clearly too small to share without invading people's space, so I would think it unreasonable and rude to ask to "share" such a table. I reject your assertion that you are in the majority.
(I would consider my patience to be demonstrated by the length of my reply to your points...!)