I'm most familiar with the C-130 but I believe it's common on many types: the pad is replaceable but in order to do that you have to remove the entire brake ass

I'm most familiar with the C-130 but I believe it's common on many types: the pad is replaceable but in order to do that you have to remove the entire brake assy, which means it's more efficient to just slap a new assy on and send the worn one to 2nd line to be rebuilt/overhauled. Often that 2nd line is subcontracted out.