Just my feeling & understanding, firstly that the car was pretty too fast through the corner to control, but also the spectator zone was not rightfully placed at the accident spot, as the driver will not be able to see below the horizon so that he could have avoided it... At those speeds the drivers will have limited sight called 'Tunnel Vision', which means the more the speed, the narrower his eyes will interpret creating the tunnel-effect, so there is little chance that he would have seen the spectators in time to avoid the mishap. So I think the safety implementation of the spectator zone the main issue here, if the spectators had not violated the organiser's safety guidelines.
I request everybody out there to spectate to think wisely where to decide to take place to spectate and make sensible decisions. If you are a first timer on a rally stage, its better to ask the rally safety officials [who can be identified by the special apron they wear] and never deviate their guidance, which is mostly vital and also ensure to stay as much away from the stage. An experienced knows better, so you can take guidance from them too. I have also seen a few people drinking and spectating, which is NOT really a good idea as it slows-down your reflexes to react in case of such incidents. I know people are there to enjoy, but not at the cost of risking their & others lives, so just take care of yourself and others around you. There is always another rally if you missed it this year, but no other life, if you loose the one!
The clip of the crash [taken far from the spot].
Our sincere condolences to the bereaved.. Let his/her soul rest in peace!