It seems to me that every time I come back from a trip abroad, a new shop has opened on my local high street. I don’t know if they wait for me to go away, in the hope that I won’t notice, but it’s a regular occurrence. Since I travel quite frequently, this adds up to quite a turnover of stores. Over time, the character of the high street changes, but most people wouldn’t notice, as the change is gradual and incremental.
But if I were to come back after a year or two away, the difference would be much more marked. I would still recognise the high street, but I could clearly see it’s different. The supermarket has changed hands (again!). The post office has gone. The bank has turned into a posh restaurant. The greengrocer’s is now a charity shop. We grieve (just a little bit) the loss. This is a small example of what is called ‘reverse culture shock’.