I'm not necessarily a fan of Uber, but this is ridiculous.
If 'taxis' are legal in Sweden then there's no reason Uber should not be able to operate so long as they are obeying the laws.
Ostensibly, this is about a specific issue - distance travelled and the lack of ability for tax authorities to measure that.
Two things to know about Nordic countries:
1) They are super, super aggressive when it comes to tax things. Cheating on taxes is worse than some major crimes!
2) They are culturally anti-business and anti-entrepreneurial. I know this may seem odd given the number of startups - but their version of 'socialism' is cultural. To be a 'business person' or 'CEO' or to 'have your own company' even up until the 1980's was considered a 'dirty word'. They have this view that 'private business is immoral' in some ways. It's hard to describe. They are just default skeptical of anyone creating a business. Obviously that has evolved a lot over the last 30 years, but the underlying cultural phenom is still kind of there.
Finally - this may simply be political. Taxi entities around the world are trying to find ways to get Uber banned, and so they find an issue or concern that gives them a legal footing.
Again, I'm not for or against Uber really ...