It's common in the U.S., especially in apartments, to have rooms with no light fixtures. Instead, there will be one outlet that is wired to a switch by the door. That outlet is sometimes upside down to distinguish it from the other outlets. That gives you the option to connect a lamp to the switch to get the same result as having a light fixture. I would generally prefer that every room has a light fixture on the ceiling, but this is marginally better than having to walk across a dark room to turn on a lamp.

I mean there can be either outlets or light fixtures connected to them, generally the switched outlets have lamps plugged in though.

As I understand it (thanks technology connections), the sockets linked to light switches are made that way in case you want to have like a floor or desk lamp and turn it on when you enter the room