Is VIOLIN more difficult than PIANO?

Why is violin a hard instrument to play?  I feel it is harder for one very simple reason.  You have to use your ear!  In piano, you touch a key and it is ready to go, and makes a great sound.  In violin,  you have to get the posture correct, your finger on the right place on the neck of the violin, in the right position, at the right angle, and then add a can now see why I really value my violin teacher, and why I tell parents to be patient with their child when they pursue violin.