>>20215889There's a lot of stuff in Gen 1 left over from testing and early parts of the games creation, I wouldn't be surprised if they literally just forgot to remove it when testing graphic tiles, or maybe they had the truck closer to the edge originally. It looks like a loading truck for cargo, though there's no cranes nearby, so yeah.
That, or it's literally just an Easter egg in the game, or an in-joke for one of the graphic artists.
