It's hard to lounge, or recline comfortably, in the lounge, or waiting area, of an airport terminal. Maybe they shouldn't call it a lounge.
Lounge comes from the French s'allonger meaning "to lounge about, lie at full length." Whether you're talking about a room with seats in a hotel made for waiting, or a nice comfy sofa, or the act of reclining comfortably, lounge has everything to do with making yourself comfortable in one spot for a while. It also means to hang around in an easy way, the way you might lounge around the poolside area in a luxury hotel.