Users of autonomous systems, or just about anyone using a computer (desktop, laptop, tablet, handheld), can easily comprehend the importance of keeping their devices secure. What, exactly, that security will entail, of course, depends on the device and its ability and requirements to communicate with other machines and systems.
For makers and users of increasingly automated vehicles–like cars–keeping malicious programs and people away from the controls of the vehicle should be more important than any aesthetic choices and equal to environmental concerns. Users must be aware that people and programs could break into the operating systems of their vehicles and make them perform in unanticipated and negative ways, and makers of the vehicles/software must constantly work to keep such intrusions as limited as possible.
That the software of such vehicles are vulnerable to outside programs seems an unintended but unavoidable consequence of the technology itself. Just as markets, elections, and choices in general (by marketing, for instance) can be rigged, so can technology. A drug like piracetam, for instance, has specific targets when prescribed by a physician. Since the drug can be purchased without a prescription, however, its ‘off-label’ uses are vast and hard to trace specifically. To me, the piracetam and autonomous vehicle have a few things in common, and one is the importance for the consumer of investigating what she is purchasing and the risks involved for herself and others.
For more on this topic, see the case of someone trying to raise awareness about this issue: http://venturebeat.com/2016/11/12/before-you-sign-up-for-a-self-driving-car-pay-attention-to-hacker-charlie-miller/