When on the ferry between Britain and either Netherlands or Ireland, there's a trucker's lounge. Only truckers allowed. Why do the ferries have this? I can understand the point of the Stena Plus Lounge — additional cost for additional luxury — but why the truckers lounge?
Because truckers are a solid source of serious revenue. If each truck brings in (say) €500 of revenue, and all it takes to get the driver to choose a particular ferry company is a €1 cup of coffee and a spare room with some daggy sofas, offering this as a "trucker's lounge" is a no-brainer.
Incidentally, this kind of thing is pretty common at highway rest areas as well, and long-distance bus drivers in particular know exactly where to go. Fill up your truck here and get a free cup of coffee, or better yet, drop off a busload of passengers for a break and get a free meal.