The Swedes must be great animal- and nature-lovers so that all the creatures of nature trust them so much. Maybe even spiders won’t bite them.
I don’t think the animals in Sweden in general are like that - they also have wolves, for example, and they are considered quite dangerous. That’s why I wonder how those in the park had become so tame.
I did a search to see if I could find anything about the Swedish park, but didn’t find anything. It seems though that tame squirrels are quite common. Here’s some videos from London and Croatia: