I don't know the percentage B2B vs consumer-focused startups in EU or US so giving a few examples makes no real sense but Spotify, iZettle, Skype and Pirate bay are all of swedish origin. And business taxes in Sweden are among the low ones in OECD. Salary (after tax) is lower than in US but schools and health care is free so compared to US the living standard is not that bad, i.e. assuming the original poster assumption is correct, I don't think taxes is the explanation.