1. As I do not have postcards I decided to look online. I found the following links.
In the postcards the places are idealised. You cannot expect to see in a postcard a bad, miserable weather. Even in the postcard from London most of the skies are blue. For somebody who lived there, they know how seldom that is. Even makes me thing if in the post production they changed how bluish is the sky, that they make it look a little bluer than in reality. In most of them the lighting is perfect. The images are visually pleasing; they invite you to visit the place or to keep some idealised memories. You do not see a road full of traffic or anything that can make you feel stressed. Sometimes electricity cables have been removed. Also, some retro filters have been added in them to make them look like more like a fairytale etc.
I think I agree with Fay Godwin. Our experience of a place is seldom related with we can see in a postcard. Even in the past when I was looking of postcards of my hometown I always found them beautiful, but not really what I could see and experience in my daily life. But is not the same with photography or painting in general? Any photo is capturing a moment which in most of the cases last less than a second. Any two photos cannot be exactly the same. So how should we expect something that last such a short time to be the same as what we experience in hours, days or years in a place? Also, even basic editing change what we look. Or post production in general in a second can change the colour or remove things we do not want to show. A postcard is not a photojournalistic photo, there are no rules what you can change or not! It did not mean to represent reality.
2. I think it is a stage of mind and a way of looking. The photographer should look things in a different way than other people do. Even familiar places should be looked with fresh eyes. Some people can switch to a different state of mind and achieve the tourist way of looking. But I think that in general it is easier to capture moments in a new place. It is the feeling of discovery. The capturing of something you did not capture before. It is more interesting to be in new place, search for new things. It motivates you more in a new place to walk around and discover. At the discovery point it is maybe better not to have done a lot of research for the place you are visiting. On the other hand, if you have done your research you cannot miss any important landmarks on the place you visit. So, in summary I think it is possible not to be a ‘tourist’ or ‘outsider’ as the maker of landscape images, but you have to ‘look’ as being one of them.