This is especially true in countries where the cars are delivered by container ship. You can easily make headlines about "Tesla has record sales in <month>" and "Tesla has poor sales in <month>" based on which months the ships arrive and the cars are delivered to customers.
I'm not sure what about this indicates that they don't have inventory control.
This is often due to the bulk deliveries at end of quarter and only really having 1 model "per line" vs other manufacturers splitting their car lines into several variants.
When a ship arrives with imported cars, the majority are likely already spoken for with pending orders and will be delivered within a month.
Tesla has been fairly consistent on this and as far as I know it matches how most auto companies account for sales. The difference is that some companies count cars sold to dealerships, even if they aren't sold to an end customer yet, but Tesla does not have franchised dealerships.
It doesn't in Tesla's books in how they report sales. A sale is only considered complete, and revenue recognized once the customer takes delivery.