I realize this happened in Sweden. My dad was a professor at the Karolinska Institutet in Stockholm; I practically grew up there. My first name is spelled "Kristian" for this reason.
Yes Sweden is very different from the US. In fact, seven years ago some Swedish cops on vacation in NYC became somewhat famous and drew significant attention (at the time) to policing issues in the US[0]. People in the US were literally saying "WE NEED SWEDISH COPS".
That said... Even by Swedish standards (of which I'm familiar) I find it very, very, very hard to believe the government would bother to do an initial investigation, draft and apply for a warrant, serve the warrant with SIX police officers, and then walk out with a handshake because some guy in the office says "we don't have that".
Meh, police get the address wrong sometimes. I could totally see them either not understanding of not believing a 'no logs' policy.
So they get a warrant for 'servers with client connection logs' and when they arrive they discover that there are no servers - nothing with a HD and certainly no storage systems, and then they contact their boss and are more willing to re-examine and maybe decide to trust that the company was being honest.
Mullvad don't say they weren't searched, just that nothing was taken. They informed the police that what they wanted didn't exist and demonstrated it to the police/prosecutor's satisfaction. Cops have access to technical consultants if they need expertise to verify this.
Good code and wiring probably helped - if there's a rat's nest of cables running into the ceiling it's hard to trust, but if there's a really clean patch panel and short direct runs between equipment it's easier to demonstrate that what you see matches the device map and how it's configured.
Yes Sweden is very different from the US. In fact, seven years ago some Swedish cops on vacation in NYC became somewhat famous and drew significant attention (at the time) to policing issues in the US[0]. People in the US were literally saying "WE NEED SWEDISH COPS".
That said... Even by Swedish standards (of which I'm familiar) I find it very, very, very hard to believe the government would bother to do an initial investigation, draft and apply for a warrant, serve the warrant with SIX police officers, and then walk out with a handshake because some guy in the office says "we don't have that".
[0] - https://www.youtube.com/watch?v=izdfnHBMwSs