Let me explain: On a string or wind instrument so many physical variables enter into the intonation and the timbre of a given pitch that it must be an enticing impossibility to think one can actually repeat a tone.
On the piano, on the other hand, it is easy to get the illusion that a tone can be repeated. All one has to do is play it twice exactly the same way: same finger, same force, etc.
But repetition leads all too readily to lack of attention. How to deal with this dilemma? Call attention to the ever so slight variables that make it acoustically impossible for a given tone to repeat exactly, even on the piano. Experiment with changing the finger, or the position of the finger on the key.