That's ETOPS vs. 3/4 engine aircraft, I believe, but I don't think the maintenance and reliability standards are appreciably different for civilian 1 vs. 2. Mainly because no scheduled service is done using a single engine, so it doesn't even come up.
I'm pretty sure military maintenance standards are so entirely different that their extensive experience with single engine aircraft isn't meaningful -- plus, their singles are mainly either very military specific (F-16 and other light fighters) or historical. Most of their transport aircraft have something in common with commercial, now, except maybe C-130s. And the USN has generally favored twin vs. single for "reliability over water" anyway.
I'm pretty sure military maintenance standards are so entirely different that their extensive experience with single engine aircraft isn't meaningful -- plus, their singles are mainly either very military specific (F-16 and other light fighters) or historical. Most of their transport aircraft have something in common with commercial, now, except maybe C-130s. And the USN has generally favored twin vs. single for "reliability over water" anyway.