Just because we can't see a means doesn't mean there isn't one.
Or am I missing your point?
It's created with certain goals in mind, to solve a problem.
There may be side effects that are dangerous, but I don't see those dangers as being any different from any other tool.
The assumption seems to be that an AI system will somehow transcend the purposes for which it was built, or that we will seek to build a replicant, in the sense of literally reproduce a human in silico.
That goal seems kind of unrealistic to me, because it doesn't accomplish anything, because we already have humans.
However, people do all kinds of things that don't make sense--but then that is a problem with the humans designing the AI, not the AI per se.
I'm probably not explaining myself well, but basically I think whenever you create something (as opposed to it randomly evolving), it has a purpose. That purpose constrains the design and/or affords constraints. To the extent the maldesign comes about, though, that is a problem with the designer and not the design.
I guess I just don't see super AIs coming about and deciding humans are worthless, unless humans design them that way, in which case that's a human problem, not a design problem.
Humans are self-interested because that's how we evolved. AIs would come about because we created them to do something. If we choose to design them to do something malicious, it has to be a reflection of our malice, not the AI.
More directly to your question, the vulnerable server isn't the danger, it's the hackers who hack it. That's not to say that there shouldn't be security concerns, but to me it is a different use of the term "safety," closer in meaning to "vulnerability." People aren't talking about vulnerabilities or errors in AI, because that's just a computer bug-vulnerability problem. They're talking about AIs being a threat themselves.
Why?
Because typically people design things to solve a problem, and those problems have constraints. Your automatic vacuum cleaner wouldn't try to kill you because it wouldn't be equipped to do so, and to the extent that it might be potentially deadly, it would be treated as an extension of pre-existing problems (e.g., robotic lawn mowers can be deadly as a side-effect, but so can mowing your lawn with an old-fashioned gas mower).
Underlying these fears I think are two classes of problems:
1. The idea of a general-purpose AI. The problem with this is that this probably won't happen except by people who are interested in replicating people, or as some sort of analogue to a virus or malware (where rogue developers create AI out of amusement and/or curiosity and/or personal gain and release it). I would argue then the question is really how to regulate the developers, because that's where your problem lies: the person who would equip the vacuum cleaner with a means of killing you.
2. Decision-making dilemmas, like the automatic car making decisions about how to exit accident scenarios. This is maybe trickier but probably boils down to ethics, logic, philosophy, economics, and psychology. Incidentally, I think those areas will become the major focus with AI in dealing with these problems: the technical issues about hardware implementation of neural nets, DL structures, etc. are crazy challenging, but when they are developed, I think the solutions about making AI "safe" will be "easy". The hard part will be the economics/ethics/psychology of regulating the implementations to begin with.