That's a fair point, and I'm wrong to imply that, at least in the case of the "Loot Train Battle", that the problem is with GRRM, since IIRC, the books have not

That's a fair point, and I'm wrong to imply that, at least in the case of the "Loot Train Battle", that the problem is with GRRM, since IIRC, the books have not yet reached that plot point (and I haven't read the books). But I do think it's fair to still critique the TV show, fantasy trappings and all, for shallow and inconsistent world-building and logic. The Loot Train Battle is an event that is symptomatic of the showrunners rush to wrap up the sprawling threads that they so carefully rolled out in the earlier seasons — by season 7, teleporting across the continent was just an accepted thing, and that correlated IMHO with a rise in incoherent and unsatisfying subplots. What I liked about the early seasons of GoT was that even for a fantasy world, there was a real sense physical space. Many of the 1st and 2nd season's developments arise because distance is a factor — e.g. the time it takes to go from Kings Landing to Winterfell, from Winterfell to the wall, etc. The Red Wedding results because the only sensible crossing from north to south is controlled by a long-declining minor House. Not sure how the showrunners could've worked around GRRM creating an improbable situation where Kings Landing is supplied by The Reach/Highgarden (again, haven't read the book, so maybe this is not the case?). But the showrunners seemed dead set either way to depict a big dragon-vs-army battle, logistics be damned.