If you think "penny pinching short sighted know nothing accountants" are the cause of a small team, I think you perhaps don't understand the domain involved.
To borrow a popular phrase, modern jet engines are literally made of black-magic fuckery. The advanced metallurgy and fabrication techniques that go into their design and manufacture are such that even if you wanted to double or triple the size of one of those teams, there may simply not be enough people in the world today who have the requisite background. And it's also not a matter of "oh, just go read these papers and get up to speed"; the engine manufacturers derive most of their advantage from the fact that they can do things nobody else can do, and they don't publish all the deep stuff they know.
Mechanical engineering PhD student here. I'm skeptical that there's a shortage of the engineers needed for this.
I know someone who interviewed at a major jet engine manufacturer. I don't know if he would have got the job or not, but he had no interest in working there after the interview. From what he described the place seemed to be a hybrid of the worst of academia and corporations. Publish or perish, poor job security, bad location, etc. I don't recall what the pay was, but I don't think it was spectacular. I won't be applying there when I graduate. If they really needed more engineers, I think they would be making the place more attractive to work at.
Some representatives of the company visited our research group once after the person I mentioned graduated. I didn't get the impression that the company was short of people in their jet engines division aside from one area they mentioned (and there's no shortage of qualified people in that area at my university). Plus, one of the people who was doing the interview actually said they (partially) transfered out of the jet engines division. I got the impression the jet engines division was downsizing overall.
Also, assuming that required knowledge is not public, not documenting important internal developments is a bad practice. I doubt jet engine manufacturers make this mistake. The company representatives, as I recall, seemed to want someone working specifically in the area they were looking to hire, but they didn't seem to need someone who was familiar with the exact methods or materials they used. Learning on the job is probably part of the job description.
I think I misremembered some details now. I'm not certain that their PhDs have "publish or perish", but they definitely have poor job security. The guy I know interviewed at the company's gas turbine division, not the jet engine division. And I think the company representatives were from the gas turbine division as well. The two are obviously related technologies and I would not be surprised if there was overlap between the divisions. Overall I still don't have reason to believe there's a shortage of qualifies engineers in this general area.
To borrow a popular phrase, modern jet engines are literally made of black-magic fuckery. The advanced metallurgy and fabrication techniques that go into their design and manufacture are such that even if you wanted to double or triple the size of one of those teams, there may simply not be enough people in the world today who have the requisite background. And it's also not a matter of "oh, just go read these papers and get up to speed"; the engine manufacturers derive most of their advantage from the fact that they can do things nobody else can do, and they don't publish all the deep stuff they know.