Surprised the lightning connector doesn't put out sound directly.
Sorry you didn't get an answer from the forum, and thanks for coming back to us with the answer.
Apple are likely expecting that Bluetooth will become more and more prevalent. At least that's all I can think of. My car doesn't have any capability for playing output from iDevices, and I use the headphone output in my truck. Transport-wise, I haven't joined the 21st century yet.