I agree with you. It has always been my hope that these oversights are a direct result of the projects struggling to find a baseline level of value rather than any underlying lack of forethought.

The level of security and approach to security will largely correlate to the types of messages that such a system ultimately needs. This sounds obvious, but I think it really isn't. In a world of self-driving vehicles with lidar + optical sensors, how much v2v communication is required beyond the sensor data?

Until that question is answered, it might not make sense to primarily focus on the security and reliability of said data.