Legally, I suspect both cases would be handled the same. Real time speech to text for private use should be legal. However, Audible has to license content from

Legally, I suspect both cases would be handled the same. Real time speech to text for private use should be legal. However, Audible has to license content from copyright holders, which gives copyright holders a certain amount of power over Audible to force them to not offer such a feature, independent of the legality.