Alber
Yes sir, airlines are 100% USDA prime AMT. May be a result of market saturation. If an airline held a repair station liscence they would need a "buy back" system of inspectors to employ non AMT's to perform hangar work. We have inspectors only for eo/ea and job cards as required in the HGR, Many AMT's hold RII certs on several type aircraft on the line.
At my company we have a A/B and C scale of pay, A being well experience stand alone line guys, B being new hires with little help needed to advance, C being employees with a cert but no experience, they go through a manditory training program exposing them to hangar/sheetmetal/avionics and shop work before they can have the "trainee" tag lifted off them. This is not common but a great chance for a non experienced AMT to get experience and on a track to great pay. I am topped out, started at the A scale and found avionics and line MX as my meal ticket and passion.
I have been a blue water to avionics mechanic/ flight mechanic/MX rep/ maintenance controller and MGT staff at several MRO's and airlines in the states. The closed door meetings at the MRO's made me disrespect the MRO business here, I blew it off as "hey I am just doing my job" for a few years until the discontent made my BP rise to an unhealthy level.
As for the requirement, if an airline has a repair station liscence they could technically hire non AMT's as said above, there is also a "repairman" certificate that an airline may still be able to get for a non AMT but it is unheard of these days.
The MRO business is crap here, hell I had a liscenced kid working for me who would not give up his B scale (not my current employer) for a tickeded A scale because he would loose his B scale seinority that gave him preferential bidding for days off and vacation slots. These kids have no pride and I am not an old man to say this.