I wasn't thinking about eating out in smart restaurants alone. I think few of us do that. Most people seemed to be talking about the trivia of going into an ordinary eating establishment alone.
By the time I reached the stage, when travelling on business, where I did go into a smart restaurant on my own, I had been eating out alone in other much more ordinary establishments for decades.
Your last paragraph, illustrates your own lack of understanding. Empathy and confidence are words people love using to attack others. there are very few people around who are truly confident. But there are people who realise that everyone else is as lacking in confidence as they are, so can put on an air of confdence, whether they have it or not.
The circumstancs of my childhood were such that I had to face a lot of situations alone at a much younger age than others. I quicly learnt that the best tactic was never to make a difficult situation worse by drawing attention to myself. So I would just act like other people around me. It is not a question of being confident, i wasn't. It was a question of appearing to be confident, that was the best way of blending into the back ground. It was looking at a situation that could be intimidating and frightening and then dealing with it in a way that was likey to ensure it wouldn't be so
Which brings me to the question I have asked all the way through this thread and no one has addressed: Why if people are very shy and used to keeping out of the limelight do they think that people are watching and commenting on them all the time? I am not talking about events that push you into the limelight, that I understand, but why would anyone pay them any attention doing an ordinary everyday events like going into a Costa Coffee and buying a coffee when alone? Especially when you can see people eating and drinking alone and doing lots of other perfectly normal activities on their own.
I actually better understand people who are uncomfortable eating in a group, where they could and possible might be under scrutiny.