I imagine that their market penetration in Europe in so tiny that they can experiment with new models without pissing in too many people's Wheaties. Don't expect this in the US anytime soon.
In Slovenia (small country in Central Europe - so quite far from the HBO Nord AB countries.) they're pretty known (and available everywhere - for money of-course). And the article is wrong - we got HBO Go some months ago too.
In Romania, cable companies have pirated HBO for years. They just offer it free to their customers. Recently, some have cleaned up their offers, but you can still bribe the cable tech for a trifle so he unblocks HBO, apparently.