/lit/ - Literature

So I've been reading this for a couple of days and I'm enjoying it a lot (Fucking Ignatius it's the sanest person around here) but I found something particullary interesting. The pic related is the edition I'm reading right now and it surprised me how, no matter how much I've flattened it, bended it and overall manipulated it while reading it it's spine hasn't cracked nor there is any sign of damage on the spine itself. I'm almost at the end of the book so you know I'm aplying pressure while reading it but yet there is no damage to be seen. Why don't all books follow this type of spine? I can't make a photo but it's basically like a yellow paste right between the spine and the pages themselves.