"Youtube don't block ads in any country. it's the turkish ISPs or government who is blocking ads if they are really being blocked. I promise you, youtube is not blocking their own ads.

When youtube shows an ad, it's not only you who earns money - Youtube also earns money. So why on earth would they block their own ads and dissable their own source of income? -They will never do that, unless forced by government/local restrictions. "

If there's no ads in turkey it's either because noone is buying that ad space, or someone is blocking them due to local restrictions (ISPs, government etc.)
It could possibly be a bug, but that don't make any sense, how a bug would only occur to videos when played in turkey.

This kinda sparked my curiosity, but I'm certain people in Turkey will have a much easier time finding out why ads aren't shown, than a foreigner. All I can do is a google search and read up on laws.
(Youtube is affected by all sorts of weird laws. An anti pyramid scheme law in Denmark dissables youtube from letting danish youtubers monetize their videos, unless part of a network)