Isn't the conduit inside the ... whatever ... plaster? ... you put over the hard concrete wall, I don't know the name in english?

It's definitely not protruding in my home... and it's all conduit in the walls.

Drywall is common in north america. It's ~1.25m×2.5m×1cm sheets of gypsum sandwiched between a heavy paper, and plaster is only used to bridge the seams. It's almost always screwed down, and adds significant rigidity to a stick-framed wall. Cement walls are often (but not always) finished by stick-framing a false wall and then screwing the drywall to that.