I have heard it said that Kane shoots early and in other words the GK is not ready and therefore cannot react. Other lesser mortals such as Sissoko perhaps give the GK more time to react and do not have the same power on the shot. Whilst Kane has missed/ failed to score similar attempts his ratio of goals to chances is much higher. This is not the first time Sissoko has failed to put away a good opportunity and the more it happens the more he will try and make sure he is on target resulting in less power and more likelyhood of the GK saving. Vicious circle which will only be broken by practicing shooting and finally scoring a few to get more confidence.
All the best strikers take them early. Ronaldo, Messi, Suarez, Aguero, Kane etc. It's what sets them apart from the rest. I seem to remember Lineker/Shearer talking about the importance of taking the shot before the keeper is set when analysing Kane a couple seasons ago.