No, they dont, but you can buy refurbished A300-freighters from EADS.
There are big differences between airline and GA business models. A shorthaul aircraft in the airline business needs to fly around 3500 hours a year to earn its keep, a longhaul aircraft around 6000 hours a year. Most GA aircraft do not more than 500 hours a year and many do less. Reliability is a key factor for airlines as they cannot spare extra ground time without schedule problems, therefore high reliability is one of the main selling points of airline aircraft. GA aircraft have a lot more ground time which can be used for maintenance and usually do not reach the same reliability numbers as airline aircraft which isn't really a problem after all with all that much spare ground time.
That said most airlines pamper their engines. For example we wash engines around every other week during scheduled maintenance, of course continous monitoring is absolutely standard with downlinking engine parameters from every few minutes to several times an hour via ACARS/datalink and rigorous maintenance action. As changing an engine is often times faster (around 6 hours for a PW4000) than doing extensive maintenance on the wing we are not against taking them off, however a complete overhaul is a rare thing, it is usually just a parts change. That requires several spare engines of course, but again, that is standard airline operation anyway.
And of course reduced thrust when you do not need full thrust is another measure to increase engine life and at the same time reduce maintenance cost. If full thrust is needed we use it of course, that is why we bought it in the first place. We do use full climb thrust now wherever usefull (doesn't really help with a low level off altitude like london area departures) to save on fuel, so reduced thrust is only used for take offs up to 1000ft AGL. Of course that means nearly every time that climb thrust "reduction" is actually an increase in thrust.