I think they already confirmed that everyone has those voices/feelings etc.
Like the murder victim heard that she is supposed to "own your truth"
And last episode the dad that was looking for his son heard the music, just like Ben.
I feel bad for Michaela. She made a poor choice, but if Evie insisted on driving what was she supposed to do? cuff her? Maybe it´s weird but I feel worse for Michaela than for Evie. Sure her death is tragic, but she kinda pressured Michaela into that situation.
Isaiah literally just heard the gunshot. There was nothing supernatural going on with him. Although it is kinda weird how quickly people became so religious about the passengers. But I guess it is a big deal when almost 200 people suddenly return, without aging.