"The coffee is not without milk."
Translation:Kahve sütsüz değil.
Just to weigh in on this debate (US speaker, but I've lived in the UK), this is still bad English.
"The idea is not without merit," would be a good example of where we use this kind of double-negative, because we're talking about more abstract concepts and using it as a rhetorical device. That sentence would likely be followed by a total rejection of the idea in question, because the speaker/writer had something better in mind.
But "The coffee is not without milk," sounds like an English speaker who's trying very hard to sound British. This type of phrasing makes no sense when referring to something like food or drink. If I told a waiter I was lactose intolerant, I'd expect them to reply that the coffee has milk, not that "the coffee is not without milk."
I understand that this sentence is probably to help us understand how to use this case. However this is not proper English. In english it would be absolutely wrong to say "The coffee is not without milk" you would say "The coffee has milk", you would not use a double negative "not without". This is a fairly basic grammatical rule in English regarding not using double negatives
It helped me for this scenario to think of sitting in a cafe and ordering coffee without milk, using those words. (Maybe in this cafe it's customary for all coffee to have steamed milk.) But when you get yours, it has milk, so you say to the waiter, "This coffee is not without milk."
Correct in the examples you gave, however as a native speaker "The coffee is not without milk" is not something I would ever say in English. In clgibbons example as a native speaker I would phrase it differently, like "This coffee has milk in it" or "The coffee is not black" or "I ordered the coffee with no milk" or "I ordered coffee without milk". Just my .02
For me, "the coffee is not without milk" is very situational. Like, say you were dissatisfied with an expensive coffee and someone asked "well, do you at least like the coffee?" You would say "well, at least the coffee isn't without milk" in a sarcastic tone. That's the only way I can see a native speaker using the double negative. I assume this is nowhere near the case in Turkish.