Have you ever wondered why organic bananas are often picked when they are quite immature or cases of organic bananas are suddenly all ripe?
My guess was that conventional bananas are treated post harvest with something that delays ripening. A quick search revealed that conventional bananas are commonly treated with thiabendazole and/or imazalil.
I also found this article on the impact of conventional bananas on the environment and on workers. http://www.pan-uk.org/pestnews/Issue/pn48/pn48p9.htm