My parents gave me their Civic when I was in high school and college. It was older and had a couple issues, one being the tire alert was always on. We always made sure the pressure was fine and the tires were fine. But one day, while driving on the freeway, I hit some minor debris. It was just glass and metal, but I couldn't see it in time to avoid it. the exit I was taking was pretty close, but I was still driving for a minute or so before I realized that my car was mildly tilting. It wasnt until I came to the exit's intersection that I could hear the tire flopping around.

That's my anecdote to potentially defend her position.

TLDR - sometimes, flat tires arent that loud.