Not sure why this got downvoted; I was going to say something similar. A lot of autistic kids like trains. We tend to like trucks, construction equipment, and

Not sure why this got downvoted; I was going to say something similar. A lot of autistic kids like trains. We tend to like trucks, construction equipment, and machines in general, anything that's orderly and has a lot of information available about it; trains are a quintessential nerd interest (see: model train hobbyists, trainspotters), so there's a whole community out there to tap into. I would guess that Thomas the Tank Engine intersects trains and children's TV in a particular way that resonates with a lot of kids who began with an interest in either.