Hang on, is this DO-178B _different_ from the DO-178B now replaced by DO-178C that is about _safety_ in aircraft systems? It isn't is it. So, you're talking about _safety_ when the parent and article are specifically about _security_.
Because confusing safety and security is exactly the kind of awful goof that we're talking about here. I'm sure these car alarms are _safe_ the problem is they don't keep your car _secure_.
The security record of military procurements is... not good. Same for the financial industry. Do a bad job, hope nobody finds out, if they do insist you didn't do a bad job and hope nobody who understands the difference is empowered to do anything about it.
Let's take something easy, communications. Your generic Android phone is capable of doing secure voice communications over a distance subject only to traffic analysis and other inevitabilities.
The British infantry have Bowman. At squad level it's unencrypted spread spectrum voice radio. So, much worse than that Android phone. A sophisticated bad guy (so, not some random bloke who decided to join ISIS last week, but say, a Russian armoured division you've been deployed to counter) can literally listen to everything you say, seamlessly, without giving away their position. Brilliant.
Now regulation _can_ improve things by mandating something that people who know what they're doing already recommend. But you're not going to get there with things like DO-178B.
