I suppose it depends on the number of airline tickets they have to buy every quarter/year. It may be that they are very good at scheduling the crews and jets to minimise the number of airline tix. I would be interested to know if they have a contract or agreement with an airline to fly pilots at a reduced rate.
Also, if I remember correctly, it is the crew's responsibility to be at the domicile at the start of their tour. The Co. doesn't care if you live in Japan, as long as you are there when you are supposed to be. It doesn't cost them a dime, versus others like Citation Shares to fly you EVERY time to start your tour.
Just my humble opinion... from a NJA hopeful.
I guess that's another point - new hires probably want to fly with them so badly that they sacrafice Doms for the bigger picture. I know I would. It's not like they have a shortage of applicants...