Why is that...if you happen to know?
Hmmm, if not legally "in your house" where might one crate a dog in Sweden?
Do they even sell crates in Sweden?
Well, the law is quite strict here. Dogs under four months may not be left alone except for very short periods of time, for instance. It is against the law to crate dogs as well as to have them in small playpens. If you have a crate, it mustn't have a door (so a crate with the door fully removed seems ok but not one with a door that can be closed).
A few exceptions, though (apart from at veterinary hospitals if the dog needs to rest or be kept in isolation): at shows and during tests there are sertain regulations, and dogs may be crated for transport. We have a safety crate in our car, which Castor is in when we drive. That's another law here... dogs must be crated or belted in the car.
These regulations are motivated by research on the psycholocical well-being of animals; the Swedish Board of Agriculture cites numerous studies motivating the law.
And to answer your question, yes, they do sell crates here, and I am sure there are people who crate their dogs, although it's against the law.
Certain things differ between our countries and the way animals are kept. Neutering is still quite rare here, for instance. There are no strays, so neutering is not required for that reason, and I would think there's also the idea that the gene pool would be undesirably small if many dogs were neutered.