Yes, you would expect some trace of the plane to have been found by now. But some people seem to think it’s impossible that it could not have been found “in the twenty-first century” or “in this day and age”. In fact, there is nothing about 2014 that says that answers must be found within a few days, or ever. Things can go wrong, and it’s still a large world, especially over the ocean.
For those who had relatives on board it must be incredibly painful knowing that they are probably dead, but not knowing for sure and therefore leaving room for a very small hope which, if they can think about it dispassionately, they understand is unrealistic.
In the course of time wreckage may be found and perhaps there will be evidence about the causes of the plane’s disappearance. Meanwhile, we might reflect that although we are an amazingly clever and successful species, we are a long way from totally controlling the world, even though we like to imagine that we do, and we do not have the answers to everything.