Well I want to agree with you, but that's not how I read the rules.
Valuable consideration IS defined in the ANO, and is pretty wide ranging. Crucially it hinges on whether the consideration (whatever it is) is nominal. Purely my own interpretation, but an hourbuilders gain could never be described as nominal, whilst the pleasure of helping out a friend could well be. If it was an hourbuilder fetching your sick aunt it could be argued that it's illegal because of the valuable consideration received.
It wouldn't be the only piece of legislation that required an assessment of motivation. That's the essence of the distinction between murder and manslaughter isn't it ?