As in Iraq, the Afghan army is having a hard time finding qualified people for technical jobs. People who have the qualifications are in short supply in Afghanistan, and most of those that do exist can either make better money in a civilian job, or have left the country. Moreover, Afghanistan has the lowest literacy rate in Eurasia (about 40 percent), and even some of those who are literate, are barely there. The skilled labor shortage that existed in Iraq, is much worse in Afghanistan.
As a result of this, NATO and American trainers have to recruit and educate a lot of their own technical people, after first improving the literacy skills of promising candidates. But then, when you've trained, say vehicle mechanics, you often find that they will leave the army (often just deserting) for a better paying civilian job.
Thus you have the familiar pattern where, new equipment, say trucks, are delivered to the army or police. After a while, most of the vehicles become inoperable. This is because of the chronic shortage of qualified mechanics and operators to maintain these vehicles. As a result, after a year or so of use, these vehicles start to break down, and there are not enough qualified mechanics to keep the vehicles operational.
It's not a problem unique to Afghanistan. For over half a century, Arab nations in the Persian Gulf have been importing Western mechanics to maintain their growing fleet of civilian and government vehicles, and military equipment. This was brought about by the lack of literacy and technical education in the region. That's because, before the huge quantities of oil money began to arrive after World War II, most of the Persian Gulf Arab states were still living in a pre-industrial culture. This was particularly the case in Saudi Arabia, where the average life expectancy was about 40 years and most of the population was illiterate half a century ago. Even today, 15 percent of Saudis are illiterate. The oil wealth led to a huge growth in education. But, unlike in the West, the Saudi emphasis was on non-technical subjects (especially religion). Thus there were never enough people who could fix things. This is still the case. Afghanistan never had an explosion of oil (or any other kind of) oil wealth. Currently, over 60 percent of Afghans are illiterate.
It gets worse. Until the 1980s, automobiles were relatively simple mechanical devices. Enterprising locals, even if illiterate, could figure out how to maintain and fix motor vehicles. But after the 1980s, more and more electronics were added to cars and trucks. Current vehicles have dozens of microprocessors to make them run more reliably and efficiently. But now you need diagnostic computers to find the source of problems, and skilled (and literate) mechanics to make the repairs. Afghanistan does not have enough of the equipment, and trained mechanics to use it. Nor do they have a large pool of literate, and technically inclined, personnel to do the work.With modern vehicles, all those computers and the accompanying test equipment, require some reading ability.
But even if you have a literate Afghan, who is into technology, they are still not as technically adept as your average Westerner. There's a tendency to let things slide, and to do a job that is just good enough, and not a little better (that will result in better performance, and a longer period of time before the stuff breaks down again.) A lot of this has to do with the custom in Moslem countries of dealing with things like broken down vehicles by saying; "It's God's will" and walking away. In the West, the attitude is that, "God helps those who helps themselves," and let's get these vehicles fixed and keep them fixed.
Lastly, you have the fact that many Afghans aren't particularly fond of being corrected. They are accustomed to ramshackle equipment, and half-assed repairs. They also tend to be reckless (by Western standards) in how they drive, or fly aircraft. This leads to a lot more accidents, and many hair raising stories by Western troops, often advisors, who have served with Afghans. But there are so many things that can kill Afghans, that the self inflicted risks of recklessly operating poorly maintained cars or helicopters, is not a big deal.
In Iraq, there developed a tendency to just accept many of these bad habits. If Iraqis mastered some skills to a minimal level, U.S. troops called it "Iraq Good (enough)" and everyone moved on to the next item on the training checklist. A similar attitude has developed in Afghanistan, but the Afghans are not as competent as the Iraqis, and this is unnerving to Western trainers who just barely came to terms with "Iraq Good."