My condolences on your inability to wrap your head around this. Allow me to give you another example of how an operating certificate can force training costs etc. to rise. UAL did not conduct monitored low visibility approaches. As all approaches at both CAL and UAL below CAT I minimums require an autoland, it made sense to adopt the UAL non-monitored approach for low visibility approaches(no need to transfer controls when the airplane was going to autoland anyway). The FAA said "whoa CAL, not that easy, you must train all pilots on the non-monitored low visibility approach procedure to comply and allow this to be conducted on your certificate". The result, all our pilots are either in the process(757/767/777 beginning Jan 1, 2012) or will be commencing training on non monitored low visibility approaches and this training will go well into 2013 before CAL crews can perform low visibility approaches the way UAL crews do.

Non-precision approaches will be trained at UAL as the equipment is brought up to CAL standards so that we can conduct RNAV/RNP approaches down to the minimums already fought hard for by CAL over the last decade(.12 737NG/.15 756/.11? 777). Using the UAL certificate, as mature as it was, would be more difficult to alter thus requiring many years of proving runs etc. for RNAV(RNP) and even certain ETOPS procedures native to CAL.

Source,
ME