Look at what happens in countries/regions where it is relatively easy to get registration data. Every few months we go through the same cycle with Norway. You get a headline of "sales collapse in Norway - Is this the end of Tesla?" and then a couple months later you get "record sales in Norway - Tesla is as strong as ever"... Well which is it? Is Tesla on the verge of losing all their demand, or are they still getting crazy high uptake in Norway? I think it is more likely somewhere in the middle, but the swings are so hard because of how Tesla allocates it's production based on whatever internal metric they choose in order to try to make customers as happy as possible. Combine that with the occasional shutdown and other logistics nightmare and it is a recipe for problems.
So then you say, geographics doesn't matter just give us the monthly data! But then you would still go through the same thing as Norway (or whatever other country) but now, on a global scale. If it takes 1-2 months to ship something over seas, a car made in Sept destined for overseas wouldn't get counted in Sept, or even possibly Oct... So you would continue to see wild swings in the month to month where if you break down the deliveries for July - Sept, we all KNOW that you can't take 7800 and divide by 3 and expect them to have delivered 2600 cars globally each month. It is probably MUCH closer for this Quarter to looking like 1500 / 1000 / 5300. If they had posted publically 1500 deliveries in July can you imagine the ruckus that would cause? And THEN publish some number in August that was LOWER than July? OH, the media would have a field day with that!
Look, it is bad enough that Tesla already kills themselves to do crazy logistics to meet their quarterly numbers. If they could get away with it, it would be much better for the company to only tell their Yearly numbers so they stop doing all these "end of quarter push" nightmares that end up making the US service centers way over booked and not allowing them to get the proper attention to detail to each customer and then you get all these delivery issues (door dings, scratched paint, chipped glass, etc) and customers get mad, and it is already a headache. If they switched to some kind of Monthly reporting are you telling me you wouldn't think Tesla would totally shift to balance the numbers out better? You honestly think that they would just carry on as they are? There is no way, because public image is everything to them right now (look what they did in response to the car fires)...
As much as I would love to have the information because I understand the company, it would do more harm than good at this stage in the game. When they get bigger and things balance out more, then it might be OK. But I just can't see how this would help reduce volatility and uncertainty.