They do. Something fundamentally changed at some point during the past couple of years. It used to be that DDG was the best for verbatim search (meaning I want to only have results were the exact words I search for are included).
Now, even with quotes, I routinely get a whole first page of results where my terms are not included anywhere. Google generally respect the quotes.
I have noticed the same problem with DuckDuckGo searches recently.
I hope that a verbatim search function will be restored in the future; I think it's an essential basic tool for a search engine, and without it the user can be left with the impression that the engine either doesn't understand what it is being asked to do, or that it is wilfully disregarding instructions because it thinks — often wrongly — that it has a better idea of what the user is searching for than the user does.
Now, even with quotes, I routinely get a whole first page of results where my terms are not included anywhere. Google generally respect the quotes.