There are special files. Sure, it's the same data, but Schwab has to create a file in a special format for TurboTax to import. We don't know what steps Schwab goes through to prepare the files.
The availability date is set by Schwab, not by TurboTax. People have been able to import from other brokers already. If you trick TurboTax into letting you import data that Schwab says is not ready, I would assume that the data you get might be wrong. And they will not send a corrected report if they change the data prior to the date they said it was available.
