We are still reeling from the news that our American counterparts are needed on set in case any tweaks are required to the script. In fact their absence is a part of the reason why American TV production has ground to a halt.
In the UK their absence is an industry requirement. One or two Directors might invite the writer to pop in and say hi but saying hi is just about all you get to do. It's even astonishing to many UK writers that the Writer and the Director get to meet at all. I mean, what could the person who wrote the script and the person directing it possibly have to talk about?
Is this good for the programme?
If not, why is it standard practice?
One theory is that by introducing the writer to other people in the programme-making process a misleading impression is created that the writer has a useful contribution to make to that process. This could lead to people like directors and actors taking them seriously. You might end up with writers expressing a view about the script!
Then again, their absence provides a helpful person to blame for things in the script that don't work without them stealing kudos from the producer and the editors for anything that does.
Another reason perhaps is that the director and writer together might arrive at decisions by themselves. Creatives being creative? Unimaginable!