Obviously, we would need to avoid permanent setbacks - but apart from those we don't really have to "get it right first time". Many possible problems can be recovered from. Also, it doesn't mean that we won't be able to test and rehearse. We will be able to do those things.
That is, you agree with them that there must be 0 unrecoverable errors, but you think the set of errors that are unrecoverable is much smaller than they do?
I think we will be able to practice in a sandbox. Not practising makes no sense to me.
Here is another example of an outsider perspective on risks from AI. I think such examples can serve as a way to fathom the inferential distance between the SIAI and its target audience as to consequently fine tune their material and general approach.
via sentientdevelopments.com
This shows again that people are generally aware of potential risks but either do not take them seriously or don't see why risks from AI are the rule rather than an exception. So rather than making people aware that there are risks you have to tell them what are the risks.