I don't think putting people to prison for, say, flipping a Tesla by screwing with its computer vision algorithm is security theatre. Rather, it's accountability. I'm pretty sure most people are aware that you cannot stop a determined attacker from breaking a system (which is exactly why Spectre mitigations were implemented as soon as the vulnerability was discovered: it's hard to exploit, but still possible).
Defining a legal code for exploiting computer systems through their hardware or their software is not security theatre, it's to ensure that we have a system to punish crime.