Seems like you thrive in an environment that lacks stimulus/distraction. There is literally nothing to keep your mind occupied in that coach seat. You can't even be properly comfortable. While driving it is the same thing. You are going through rote motions, but at least the seat is comfy and you have to pay attention to the road and where you are going which provides some input to your senses and thus lessens the effect. If I am right then sitting on your toilet for thirty minutes (not doing anything other than sitting) should have the same effect. Try it... for science!
Possibly; yet when I catch public transport (train, bus, tram), I don't get the same thought processes or out-of-the-blue thinking. I'll think of things, yes, but not to the same extent, especially in terms of creativity. I can assure you from many a session sitting on porcelain thrones for elongated periods of time, I don't get any great thoughts there-and-then either!
I've found they've been generally well lit, not what I'd consider overly dim, as low/dim lighting will send me to sleep. And of course dealing with irritable passengers next to me, the person ahead attempting to crush my knees with the reclining of their seat, etc etc. It's a weird context to get creative, that's for sure.