I find the exact opposite to you.......................................................For St Louis membranes seem to come off easy, Baby backs tend to be impossible so the membranes stay on.
Are you sure the back ribs you get don't already have the thick membrane pulled off and you are fighting the inner membrane?
Back rib membranes usually come right off in one piece while any style of spare rib is a PITA to get the membrane off. I normally get back rib membranes off in 1 piece while spare membranes come off in pieces and most often some of it won't come off.
