Or that they don't want to/cant show a phallic object.
Even if they are poor, I know of a binder for £3 including shipping, or there's back supports which are safer than bandages at least. I see no real excuse for it, except that its artistic and easier.
Think about it another way, if you told your mother, that's all she'd seen, and she looked up something like "using bandages to hide chest", or something similar, she'd stumble across a whole army of cracked ribs, bruising and pain. It's not going to do you any favours in showing her that this is the best thing for you to do. My girlfriend hates me wearing my binders because she's worried they'll harm me.