It's easy to accidentally hit the microphone button that appears for any text field in almost all smartphone apps. The phone then transcribes any speech it hears and enters it into the field. I've done this.

It's not hard to imagine a scenario where the driver had the message passenger view open in the Lyft app and accidentally recorded the conversation this way. This probably happens a lot but this time the driver also accidentally sent it rather than deleting it.

This seems much more likely than a company recording someone without their consent but also texting them the transcription.