My guess is the audiotape version of the guided tour was discontinued with the launch of the SE series, and this is from experience. When my parents purchased their SE SuperDrive used in 1993/94, they did not receive an audiocassette. However, when my grandfather purchased his Plus used about a year earlier, he did receive a guided tour audiocassette. I will have to hunt down the transaction documentation to officially confirm this on the thread, but I do know for certain that the audio tour was still available with the Plus series until its discontinuation in late 1990 (the Plus is long gone, but I think he kept the audiotape in his study).
Besides, I have never seen a guided audio tour for the SE advertised on eBay, or shown on Google for that matter.