How many landfills are proper landfills, and not half-assed landfills, or just holes in the ground? Out of all those proper landfills, how many are properly maintained? Like everything, protection and drainage degrades with time.

Are you asking about any first world country, or about random third world countries?

In rich countries the norm is all active landfills are properly maintained. There are a few bad apples that are caught once in a while, and a number of long abandoned landfills that cause problems, but for the most part a landfill in any first world country is not an environmental disaster.

In poor countries people just toss things wherever with no concern.

Do you have examples of such proper landfill, as well as their cost vs capacity? It sounds awfully expensive for a trash stock pile.