Why would someone get offended if you sit in the back seat when they drive you home?

My aunt was driving me home, and I chose to sit in the back. She got angry about it, and I genuinely don’t understand why.
My reasoning was pretty simple: I like the back because there’s more space. I can stretch out or even lie down, and I don’t have to make small talk during the drive. I generally prefer being able to just relax quietly.
So yes, I was avoiding having to make small talk, but I wasn’t trying to avoid her or send a message that I didn’t like or appreciate her. I just don’t naturally see sitting in the front as a sign of closeness or appreciation.
It made me wonder whether this is partly an ego thing. Like, does the driver feel offended because they think, “I’m doing you a favor by driving you, and you can’t even sit beside me and talk to me?” Or does sitting in the back genuinely communicate something negative to most people?
Do people interpret it as:
“I don’t want to sit with you.”
“I don’t appreciate you driving me.”
“You’re just my taxi driver.”
“I’m distancing myself from you.”
Or something else?
I’m genuinely curious what other people read into this. If someone you were driving chose the back seat, would you be offended? If so, what would you assume they meant by it?