This pattern here follows that of their employment practices and money bags - a big fat gray area.
I can speak for myself having commuted for years, sometimes with less time at base than a 'minimum rest period'. Was I tired? At times yes, but no more than my colleague who had two sick kids at home. My overall well being? The flexible commuting made it possible to keep up somewhat of a family life with a newborn at home. In the mean time I never got the opportunity to transfer, even though vacancies existed at the base of choice.
While the commuting helps a lot of people that were in my situation, I think the system should be highlighted and exposed. Tighten the screws on them, issue proper tickets, pay the airport fees and let OFF day mean OFF day. It's part of levelling the playing field with competitors. They will have to take the basing issue seriously and bring back some general decency.