They don’t appreciate popular Government’s initial taxes (8)
I believe the answer is:
ingrates
'they don't appreciate' is the definition.
(ungrateful people)
'popular government's initial taxes' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'initial' indicates taking the first letters.
'taxes' becomes 'rates' (rate is a kind of tax).
The first letter of 'governments' is 'g'.
'in'+'g'+'rates'='INGRATES'
(Other definitions for ingrates that I've seen before include "They have no feelings of gratitude" , "Thankless ones" , "unappreciative people" , "They never say thanks" , "Those showing no appreciation" .)