"Poorest" is a mindset. If you consider Kathmandu alone, it is not that poor. Kathmandu Metropolitan collects lots of money in taxes. I assume the airport, being a monopoly, collects good revenue from all the people traveling overseas. The international airport is in Kathmandu, not in some remote village in Nepal.
It's more in the mentality of the people who gets hired there in the airport. They need to have good management, and people hired based on their merits. If people are not doing their job satisfactorily, or if people are engaged in corruption, then they should feel the fear of losing their job. Do they even do reviews there on a regular basis in the form of management tiers?
I've been through the kathmandu airport few times, and at one time I felt pestered by one man who wouldn't let go of my luggage even though I was telling him that I was more than able to carry it myself.
Nepali government could create a good atmosphere for Nepalese who have completed their education and have work experience in the west to return back to Nepal to compete in these higher management or technology positions.
Like it or not a major problem in Nepal is nepotism, which also ties with racism. Just a thought.