Ii think due to the fact that is not meant to be used as passenger flight nobody really bothered about that.
Even if a falcon rocket is used to bring people up there.... the first stage of the rocket never will be considered mission critical at its way back to earth. It is not designed to protect anything of true value when returning.
At best its a consideration if it might be worth to add additional backup system in relation to the additional launch costs.
How much does it cost to bring a backup pump into orbit in relation to how likely it is that the main pump fails and how much it would cost to lose or repair that rocket.
The costs per kg on a falcon 9 is about 4600$ (the official aim for the cost ration is much lower but that is only if a stage is in use for at least 10 launcher - which so far never happened).
The cost per launch is down to 50mio$... but lets simply say.... its better if they put a backup pump on it.
Well... the thing is I dont know how heavy such a pump will be.
If its 10kg.... then the costs per launch would increase by 50.000$.
If this is a one in a hundred incident (who knows) SpaceX could save 5mio$ and risk one of these failures in 100 launches. If the damage is not so high and the recovery + repair costs are lower than 5mio$... then... who needs such a pump?
It is really hard to tell which solution is the best. After just one incident and without insight into the true specifications of the hydraulic system and the cost structure its impossible to say whats the better solution.
Right now there is only one real arguement that speaks for a backup system.
The reputation of the company. Its never good for the reputation when a rocket falls out of the sky.