Numerous responses pointed rightly to the better explanations: 1) you actually get more hours per day of heavy work done when you have Northern European temperatures, especially for planting and harvest, compared to the oppressive heat of the South; 2) southern regions often have more bio-competitors in more niches - parasites, pests, and toxins, which make large-scale food production and reliability difficult. Not many locusts in Sweden.
Add to those reasons for the disparity, this *Logisitical* thinking: When you have a warm region with the capacity to produce a lot of food per square mile, then you end up *mostly* producing lots of food, feeding lots of people, and all those people need STUFF! Yet, there are so many people per mile, now, that all the NON-FOOD resources are scare and expensive! You have fewer opportunities to build, create, innovate, and be entrepreneurial, because only the wealthy can afford more than cloth and grain! Thus, your own job opportunities are slim, when no one is needed in the fields, and thus, labor UTILIZATION rates are low. That's all just for hot, food-productive regions, though...
In *cold* climates, the land produces less food, so it feeds fewer people per square mile, and thus: there are MORE NON-FOOD resources, per person! Look at how Sweden, centuries ago, was EXPORTING iron ore, fish, and wood! You have plenty of materials, if you invest your time into making something out of them. There's always more work available, to squeeze extra benefits, so labor utilization is high. Still today, those Northern countries you admire all have INSANELY low population-density, which means they have a huge reserve of natural resources PER PERSON. Very efficient!
And, in northern summers, seas are hyper-productive! All those long days of gentle sunlight are perfect for fish, and that oceanic boon enriched Baltic countries far more than those Mediterranean - the Med is depleted of nutrients and has *multiple* times less fish! Fishing is good protein and at high labor-productivity, a boon to Japan too... And, having fishing *seasonally* gives you time to make repairs, and the hours you do spend at sea yield more catch, each. Also! Food *preservation* in the North is cheap and easy... which adds up. In general, those Northern countries, with lower population density, and a higher portion of food from fish and animals, are also less susceptible to *variations* in food, year-to-year, buffering against famine, revolt, and providing a stable footing for long-lived and profitable businesses.
Further, by stock-piling and shifting between activities by season, Northerners had months in-doors devoted to craft - while Southerners had no raw materials, among such a large population, to do much. The South had cereals from hotter climates, and got trapped in a High-Population/Low-Resources cul-de-sac.
