I currently work in the static analysis industry. Broadly speaking, the MISRA-C ruleset is, in my experience and in the experience of many customers who apply it, not impractical, clearly of benefit, and the majority of rule violations (including a number of rules violated by Toyota) easily found with static analysis tools.

I even know that Toyota is a customer of (at least) one of the static analysis tool companies (obviously Toyota is a huge company, and I've no idea if the specific muppets making this clusterf had any static analysis tools; just that Toyota as a company definitely has someone buying them). It seems that they either just didn't use it, or just didn't care (or were told not to care).

As an extra point of data, I sit opposite someone who is on the MISRA-C committee. He is a solid C coder who knows a great deal about the language and how to get it wrong. His day job is writing/maintaining static analysis tools for C programmes. Obviously this is no guarantee that the committee as a whole is good at maintaining the MISRA-C ruleset, but they do have at least one active, experienced and competent C coder (with lots of experience of having to actually automate detection of rule violations) at the table.