It seems like there can be little to no hitbox; in some cases, there is a tiny hitbox, and in other cases, there is basically no hitbox. I'm kinda new to the game, but I can see if there are any ways to remove it.
Edit: I should also mention that I am on the latest version (1.20.12 stable), without any mods.
Edit 2: I'm submitting of video of me removing the rusty toothed rail. I can find another way, but for now, using a stone blasting bomb and lighting it with a torch will make it go away. If you placed it near some important structures, then I can see another way to remove it.
breaking rusty toothed rail.mp4