I just hate labels that end up with normal people sitting on trains worrying that their perfectly normal interactions with their kids are making them look stupid.
This, absolutely.
I have 2 dcs with autism, and every train trip is a nightmare, making me a bundle of nerves before, during, and after. Sometimes they are pretty quiet the entire time - but it's still a nightmare for me, because I am on edge the entire time, trying to anticipate problems, head off meltdowns, and keep them calm and not bothering others around us (who for some reason feel the need to wind my dcs up by asking them questions and making "joking" comments that upset them and then sniffing and moaning when I politely ask them to please leave my dcs alone). Oh, and my younger is at a point where he gets really explosively upset if any personal information is given to anyone - and that includes explaining that they have autism & hypermobility when people are demanding to know why dcs are sitting in a disability seat or stimming or whatever.
To some extent, this is true on the bus and tube as well, although slightly more manageable as those are usually shorter trips and more familiar to my dcs.
Being booked in the quiet coach would be a massive problem for us, as moving tends to be very stressful once we've settled (if there was even an available place - and wandering the train to find one would likely end in meltdowns) and staying put would obviously not be a good option. We've apparently been lucky thus far, as we've not ended up in the quiet coach. Fingers crossed we never do.
Between autism/processing difficulties and home education, we do tend to have an ongoing narration wherever we go. I try not to be loud about it, but at the same time, I have to focus on my dcs. If one of them is struggling, I don't care whether someone else is annoyed or not - trust me, it's better to hear the calm narration going on than the meltdowns.
And yes, we bring tablets on longer trips. Again, it's to our benefit and the benefit of those sitting around us. I don't care if people judge me for that or not. We get judged all the time by people when we're out and about as people make assumptions when they see autistic behaviour and/or meltdowns.