No offense to the A&Ps, but a person doesn't need to have been raised in the US to understand modern aircraft maintanance. Some computer knowledge background is helpful, especially when working on modern, glass cockpit airplanes, but isn't necessary. Most computers are plug-and-play. Also, many of the scheduled Mx tasks are spelled-out in the shop manual. Follow the directions, fix the plane. Yes, that is over-simplified, but you get the idea.
One more reason to outsource heavy Mx: set-up costs to perform the maintanance can be high. Special rigs, stands, jigs, tools that are only used every few months can tie-up lots of cash that could be used elsewhere. Inventory is expensive as well.