Why is wave theory of electromagnetic radiation not able to explain photo electric effect? How does photon picture resolve this problem?

Wave theory cannot explain the following laws of photoelectric effect.
$\bullet$The instantaneous emission of photo electrons.
$\bullet$Existence of threshold frequency for metal surface.
$\bullet$ K.E. of emitted electrons is independent of intensity of light and depends on frequency.
The concept of photon explained that energy is not only emitted and absorbed in discrete energy quanta, but also it propagates through space in definite quanta with the speed of light. It can explain all the above photoelectric effect, which wave theory cannot explain.