Non liscenced AMT's
The FAA governs that a person performing maintenance under a repair station liscence shal have adiquite supervision. I forget the numbers but in MRO's here stateside it is often to find a 15 person crew with a lead/supervisor who has a liscence and a majority of technitions who are unliscenced . One crew could have 50% AMT's (by chance) and another with only the lead and or supervisor. These ratio's are narrowly scrutinized, everyone works under the MRO's repair station liscence (no one works for free). They get away with this under a 100% buy back program where everything is baught off by an inspector.
Things are this loose winthin the USA, airlines who use forign MRO's are subject to less scruteny as FAA oversight is more difficult to maintain. I can not speak for airlines governed under other regulatory systems.
Not saying there are any less skilled techs at these forigh MRO's, just that airlines like to take their business to where there is less oversight for a reason. I have heard first hand form a US based airline DOM who had been offered several times by a centeral american MRO to drop off his aircraft and return in a week to pay for a freshly signed C-check about 20 years back. Can't say this still goes on today but bottom line for an MRO is turning over a job with the least amount of overhead invested.