There's an infinitesimal chance that a drone could cause an airplane to crash.
It could do a bit of damage though, which would take the airplane out of service until repairs were made, a great expense.
Taking one through the engine would cause damage, but failure would be extremely unlikely.
Given the current environment, I believe a huge effort would be made to find the drone operator and hold him responsible for civil and criminal penalties.
They don't have sensors for such things.
Further, a pilot would absolutely maneuver to avoid a drone.
The problem is there wouldn't be enough time between visual detection and the ability to avoid it.
The difference between birds and drones is that birds are very adept at avoiding airplanes.
Drones are not.
I totally agree.
As a helicopter mechanic and pilot, there is no doubt in my mind that a collision with a drone, such as a Mavic could cause serious harm to a manned aircraft. As to whether or not this could cause a death, it would need to be very particular situation.
Keep in mind though, that "a plane" takes on many different meanings. The general public most-often thinks of Airliners (A320, B737, etc) because they have most of their airplane-related experiences there. The larger the aircraft, the more systems it has aboard, and the more redundancy is built into each system. (The 373 has a triple hydraulic system, for example).
There is another facet to aviation, called "GA" short for General Aviation. (aka not-the-airlines) GA Aircraft are generally much smaller, and many people are surprised at just-how-small they are (Being used to the largest heavier-than-air flying machines as 'the norm' standard tends to make one biased ; )
Examples:
R-22 Helicopter
Cessna 150
There are also "Experimental" and "Light Sport" aircraft, which make up a sizable part of the aircraft numbers in the U.S. (where I live).
I'm not 100% certain of the numbers, but I suspect Airliners are a minority of aircraft in the U.S., although they do on-average fly more flights-per-plane.
Every aircraft has vulnerable systems that need to be aligned, calibrated, rigged, etc. (I know because I provide this service) Most aircraft are built to be as light as possible, given the size they are, and there are a lot of strength-to-weight trade-offs.
Like ascension said:
Birds are wired for survival, most drones can't even look up.