Greetings
I dont agree with underdevelopped country theory, because even for classic approaches design, they had to bring in companies or consultants to do the job, and they will just do that again, when time will come, and when money will be available.
The not invented here neither, the biggest hurdle is coming from civil aviation authorities whom are reluctant to revolution, they like darwinian products, i.e., evolution.
Second you need to have Aircraft with Advanced FMS/FMC, which is not often the case for these countries.
Third They have already invested in Radio Aids or precision and non precision approaches and their money priority is not for GPS, but rather for other fields of developpement, or even to purchase food and medecine.
Fourth if you fly there your airline can desin a GPS approach, pay the flight checking of the approach, get it approved by their own authority, and the local authority and just fly it.
