This municipal railway system was, interestingly, started in 1941, the very same year that some other European railway systems were being bombed out of existence. Doubtless, the tax base that financed this particular railway was likely derived from funds obtained from trading with various warring powers (no need to mention specific countries, is there?).
In all fairness to the Swedes, nonetheless, it should be pointed out that their country's attitude towards the Nazis was often influenced by the vulnerability of their geographical location. At times in the 1940s, Sweden was completely surrounded by German-controlled countries and, as such, could have been invaded at the drop of ein Stahlhelm (Ger: steel helmut).