There are many hazards out in the real world, some of which are caused by the illinformed and un-educated. Unfused extension bars and socket adaptors, poorly installed switches and lights and shoddy workmanship can all prove extremely dangerous.
One of the worrying trends over the past decade has been the incorrect installation of halogen spotlights. These units need to be installed competently as the heat they generate is immense. Take a look at what happens when they are installed incorrectly
The most important aspect of electrical work is testing and certificating, if your chosen installer can perform these tasks, then you stand more chance that the basic knowledge is also there. Take a look when the basic skills are missing