they all seem to apply the "local fee" also to official residents (staying at least a year in the country or so).
Thailand has just removed that concession and has big notices at its NP entrances reminding such persons of it!!!!
Also I noticed that citizens of (friendly) neighbouring countries sometimes pay less than other foreigners
E.g Namibia has slight reductions for SADC members (Southern African Development Community - Angola, Botswana, Democratic Republic of Congo, Lesotho, Madagascar, Malawi, Mauritius, Mozambique, Namibia, Seychelles, South Africa, Swaziland, Tanzania, Zambia and Zimbabwe.),
That might imply that all these countires also operate differential pricing?
India has "midway" fees for SAARC members (South Asian Association for Regional Cooperation - Afghanistan, Bangladesh, Bhutan, India, Nepal, the Maldives, Pakistan and Sri Lanka)
and BIMSTEC members (The "Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation" - Bangladesh, India, Myanmar, Sri Lanka, Thailand, Bhutan and Nepal.)
And yes Nepal operates differential fees at its WHS and gives reductions to SAARC member nationals. It also gives some reductions to Chinese at some but not all sites - all very complicated!! See https://www.welcomenepal.com/plan-your-trip/heritage-site-entry-fees.html