The problem of maintenance in industry is thorny for one very good reason:- defects accumulate very quietly over time. Catastrophic failures are rare. It is often almost impossible to see or categorise a defect at all. Like measurement tolerances, defects always accumulate, they never cancel each other out.
So yes, quality is often invisible, you can take your aircraft to an Asian MRO and it will be fixed "legally" but the quality of workmanship may be another matter and that may not become apparent for Ten years.
Meanwhile our bean counter manager has made his savings, received his bonuses and has been promoted sufficiently far away from the ticking time bomb his penny pinching created.
Sunfish,
Pretty much to the point. It only has to happen once to lay the groundwork of a latent defect that emerges at the worst possible time.
The only upside is the forgiving nature of the design features of today's modern wide bodied aircraft, for without that, today's jet travel would be far less safe.