From Sweden, Stockholm, can say a solid NO. my coworker lost his backpack (wallet, iPad and Mac) in the university computer room (card key required to get in) by just leaving it for 5min under summer HPC course. When we managed to track the mac down (through cloud & GPS) it was 40km away, moving in a car.

You can usually ask someone to keep an eye out while you go to the restroom/refill coffee and most people are happy to help, but you need your due diligence

I lived in Sweden for a little bit, traveling around and into Norway and I can confirm this, at least partly.

Where it is not true is in large cities. Small cities and rural areas are one of the safest places on Earth as long as you don't get nibbled by a moose or overrun by ants.

For hours? No way. I wouldn't do that, even if I sometimes leave stuff for a few minutes if I'm in a cafeteria I know well, plus etc. etc. But not for hours. At best your stuff would be taken care of by e.g. the cafeteria personnel, if not then with that much time the statistics won't be in your favour.

In Finland, I wouldn’t leave my staff for half an hour but definitely can leave my stuff if I go to a toilet for example.

Having lived in Norway and Finland, I’d say it would be very likely that you would get your items back. And if there would be contact details, someone would have most likely tried to call you before the few hours would be up. Would more or less the same in actual public spaces as well.

Depends. Usually yes. Also wallet return rates are high / Finland.

That's cool.

Where I'm at when people (like, taxi drivers) do bother to return lost-and-found wallets, it's newsworthy enough to make its way to the newspaper.

That should tell you the status quo here.

Define "Northern Europe". With all due respect, I wouldn't test that theory for 10 minutes in Amsterdam, Malmö, Gothenburg...

In finland it depends. In Helsinki? Nope. Anywhere else? Yeah.

Depends on sex.

Sex of what, the unattended item that is about to get stolen? Or thieves can typically tell the item owner's sex by just looking at the item they were thinking about stealing?