I've seen "boxless" switches from time to time, but they're definitely not the norm. These guys just punched a hole into the wall and secured the switch with the claws. (In one case there was a surface mount switch, and they applied nearly 3cm of tile adhesive (which meant concrete back then) and tiles onto the wall, leaving a hole for the switch/Schuko receptacle combo (no ground wire, the neutral for the receptacle was one half of a 0.75mm2 zip cord put in plaster, even though the wiring was in conduit, in the other case they drywalled over the wall and just tore out the old box and mounted the switch in the empty hole).
