As we work with prototypes vehicles a question about sufficient level of safety arises as soon as they are going to hit public roads or go on a similar critical mission. In early phases of the development and in sample approach to delivery is difficult to expect all activities of the safety life cycle are already in place.
Common standards and norms either do not differentiate prototypes and series production, or just address the later.
What is still about safety for prototypes.
First of all, these are some emergency mechanisms supporting safety goals such as emergency buttons (power-off) or limitations (e.g. power train, braking or steering torque requests). Saying this not all safety goals can be covered with emergency buttons and controlled by the driver/operator. Additionally, as soon as safety is allocated to availability (e.g. ABS while emergency braking or ESP in a sharp curve on a wet road) a simple power-off solution becomes ineffective.
Another approach used to increase prototypes safety is allocation of safety to driver instructions. For example, in addition to automatic test of charging cable disconnect before vehicle start use driver instruction to check it manually. Many driver instructions will imply extensive training with added cost and time.