I wonder what will happen when they get to 99% reliability? They clean up and rebuild the Mechazilla every once a hundred catches, on that occasion that one fails?
I suspect there's already a whole "refurbishment" process for the crane even for non-reusable launches, and once it's working darn reliably, they can just have a bunch of them ready to go, and cycle once in a while.
The next one is already mostly built and very different from this one. They move fast.
I also expect if something fails a test in the way down you crash in the water rather than splat your catcher
The booster aims towards the shore until the landing burn starts, only then does it swing towards the tower. So, for the most part, failures should mean that the booster safely crashes into the water.
They've landed over 300 Falcon boosters and haven't wrecked their barges yet I expect that this won't be a major issue.
The plan is to have many, many Mechazillas.
That, and redundancy. The amount of cash you save allows you to do that.