Yes, this story, lately making the rounds.
Hobo gets on train, finds car full of bananas, dozes off, wakes to find car full of horrible hairy spiders.
Those bananas would have been loaded on the train by human workers. Did the workers not notice a massive infestation of huge spiders?
Or are we to believe that the spiders had hatched from eggs, and grown large in a remarkably short time with no food available? (Hint: spiders don't eat bananas. They suck the juice out of bugs, or perhaps small birds or unwary dwarves.)
Some years ago, when I finally got around to seeing Alien, a question immediately sprang to mind: how did the critter manage to grow from iguana-size to monster-size without, apparently, eating anything?
The same question applies here, except that we know about the eating habits of spiders. A xenomorph might feed on radiation from a starship's drive; a spider needs bugs or similar.
I suggest that an insane arachnophobe makes an unreliable witness, and there were just a few spiders. Or that the entire story, being set in a far-off place in an era with spotty communication, was made up out of whole cloth.