I'm a completely different market from you, but my observation is that inventory does not mean immediate availability.
Cars that appear on the website in batches means they're destined for a particular region. For us that means about 1 month away from actual service center (for registration and delivery) given transport and logistics.
Some cars from that batch might appear and disappear and reappear over the course of a day. Or worse you might end in a double-booked (or more) situation due to delayed issues of deposit payment, cancellation, etc.
Generally cars that show up on inventory do not last long, as demand still outstrips supply and they get matched or otherwise purchased by new customers.
I found out by having bought cars, and being told the cars mysteriously no longer exist, or having these cars disappear and reappear from my account (deposit having already been paid!!).
I'm surprised with so many people actually working for Tesla in sales, nobody's really come out and shared how it truly works.
Either way, their inventory management seems to be a mess - not truly real-time, and the staff aren't fully forthcoming with complementary/supplementary information on customer orders.