I accept all your points, but dont think it will become “the way” over here. When an agency is making a National or international TV campaign and are paying the VO possibly 5 figure sums (before the decimal) after tvrs, they will have the whole creative team in on the session and will spend hours getting it right. Its not because theyre incompetent (although not all are brilliant too) but the stakes are so high. Theyll also often have a particular engineer who they want to work with, and a particular mixer, composer etc.
I think the picture sync thing is more for tv programmes. The vo will be listening for what the in vision person is saying, and reflect that in their delivery. So viewing the programme in context can be very important, as you know.
Interesting different ways of working though across the water.
Peter