I5 Lower Volume Control Does Not Work - Come Clean Apple!

My I5 lower volume button does not work again. Called Apple support this time, support guy tells me it is a "hardware failure". I explain that when it 1st stopped working I reset everything and it started working. Support guy then also point out that my phone is 87 days out of warranty and I could pay $19 to talk to a tech that would essentially confirm what he just told me. Quite the genius, as he repeatedly called me "my man". Anyone ever wonder why the EXACT SAME PART (button) has not failed in the top location? I would love to see a root cause failure analysis and hear the technical explanition. Anyone have it?