Yes, I realize I am resurrecting a very old thread. But I have noticed in the last couple of years that I do not see postcards displayed when traveling like I used to. Even when actively looking for them, sometimes they are just not to be found. I still mail some, but also like to get them more to commemorate where I have been and what I saw. I have my pictures, but the postcard versions are often better. I was there on a cloudy, rainy day, but the postcard shows blue skies and sunshine with no annoying people in the foreground . Or the cathedral/castle/abbey is undergoing restoration with lots of scaffolding but the postcard shows the attraction without the clutter. A view from above is also nice for a large site (but hard to get without access to a helicopter or balloon)..

I found this from 2019, and that was before the world shut down. I am sure that also contributed to a further decline in postcard production and availability.
"Just a few decades ago, more than 20 million postcards were sold each year around the world, but now it has decreased by almost 75% to just 5 million. Many publishers are closing or decreasing their production to respond to the decline in demand."

It seems like another relic of travel days gone by is slowly fading away. I think that most people now would rather just message/email/text an image from their phone. However, I am not most people.