Metro lines don't tend to have much visible outside them (if anything at all save for some flashing lights), and there are extended scenarios like the Channel Tunnel where passengers basically don't see anything for over 30 minutes.
Just make sure they can plug into Facebook/Instagram/YouTube/Social Media of choice and quite literally most people wouldn't care in the slightest.
That's not to say the negative reaction of a small minority wouldn't be vastly increased, but I think the masses would still be perfectly fine.
The main problem I see with this is that both the small minority and the large majority are locked together inside a tin can speeding through the stratosphere. I'd rather not find out how fast panic might propagate under such conditions.
You say that like there's anywhere else that it matters