First of all, globally speaking, lactose tolerance is the deviation and not lactose intolerance. Just about one fourth of the world's population keep the ability to digest lactose after growing up/breast feeding, an ability achieved through genetic selection and most prominent in the cattle keeping population of northern Europe. In Sweden, only 2% of the population is lactose intolerant, but this number increases to 15-25% in Germany, 50% in Italy and even 70% on Sicily. In East Asia and the southern parts of Africa and South America, 90-100% of the population is lactose intolerant.
So why are lactose free milk products so common in Scandinavia, where they do not seem to be medically required, at least not as often as in many other countries? Why can Italians drink their cappuccino or latte with regular milk, even if half the Italians are lactose intolerant? EFSA (the European Food Safety Authority) concluded in a study from 2010 that most people with lactose intolerance can tolerate up to 12g of lactose in a single intake or 20-24g of lactose on a daily basis with no or only minor symptoms. For regular cow milk, this corresponds to a single intake of about 250ml or daily intakes of 400-500ml. Obviously, lactose intolerance is not necessarily an argument for using lactose free milk products in coffee drinks.
It is however often claimed that the alleged health benefits from lactose free milk products is merely a marketing gag. Scandinavians are mostly wealthy enough to pay extra, even just for the belief that they are doing something good for their body and soul.