Are dental crown treatments covered by health insurance or non-covered?

I wonder~ I pay my insurance premiums faithfully every month, so why are the costs for crowns, posts, and resin cores during dental root canal treatment all treated as non-covered items? A zirconia crown costs 400,000 KRW; does that mean people without money can't even get root canal treatment? Is there no word from the political sphere about converting some of these costs to insurance coverage? I'll consider voting for them if they actually do it.