I run these courses in Ireland.
It is essential to do a course as part of 'competency, which includes, knowledge, experience and being authorised as well as training.
Sure, a scaffolder can hand over and make the initial sign off on a scaffold, no problem, and he doesn't need any further training other than his scaffold 'ticket'.
The problem is that seven days later, or sooner if any event may have made the scaffold unstable, he will then be inspecting a "place of work at height".
There is a big difference between the two!
For example, you will need to know the weight of all materials placed on the scaffold and loading bays. Know the minimum width requirements for access. A knowledge of the hazards of excavation near a scaffold. Be able to note changes in adjacent electrical installations, traffic routes and causes of vibration all of which can seriously impact on the safety and stability of the scaffold.
You need training to inspect it because it is a place of work at height, not just a scaffold anymore!