Except for issue of MR, why don't you use Part 2 of the MR for endorsement, corrective action and release to service of same?
Because endorsing the MR grounds the aircraft unless you have a MEL in force.Smaller aircraft generally don't have MEL's. Operators drum into pilots that they aren't to endorse MR's unless asking prior permission.
Is the lack of apprentii the fault of the MROs or a lack of interest on the part of the young folk?
Young folk come in and work hard but a licence outcome is very hard . Aviation Australia has a monopoly on training and their assessments can take a year plus. Of course these guys aren't stupid and usually float into other trade streams or opportunities as getting a licence is too hard or expensive. Several states don't even have 147 approved training. Employers are reluctant to employ apprentices without a clear path to a licenced outcome. Risk vs reward is very low for any tradesman in aviation
Does GA maintenance require a Part 145 MRO facility?
That depends on who their clients are........