jackcarl:
The equipment required for RNP approaches alone costed more than some of the domestic aircrafts used in Nepal.
The performance model was built around the existing equipage for modern heavy iron: dual FMS, dual auto-flight, dual A/T and most expensive, three IRUs.
The concession was made for "entry level" RNP AR by not requiring one or more IRUs provided no approach segment is less than 0.30 and the missed approach is convention TERPs/PANS-OPs.
Thus, the bar is set very high indeed. In the U.S. at least most corporate operators have all the equipage beg off because of the very high administrative burdens set by the FAA (not so high for airlines with large flight technical staffs and a limited number of RNAP AR approaches in their ops specs).