Does official Apple security framework ("Apple EndpointSecurity") targeted at AV vendors serious enough for you? They themselves built an OS subsystem specifically for AVs to use, and Microsoft has done the exact same with AMSI.

There are actually very few techniques that are 99.999% effective. Cryptography when considered per se maybe is, but the wide topic of heuristic analysis is much lesser than that. Even if we consider some imagined, mythical 99.999% effectiveness, it's always measured in the specific boundaries we set during our analysis. Permission rights in the OS are 100% secure if we assume the authentication for sysop is secure. If we store the password for root in a public git repo, then OS permissions are 0% effective even if the system code hasn't changed at all. Your percent value is very fragile and relative to the boundaries we set. The unbreakable wall you think of can turn into a sheet of paper in the blink of an eye.

The cheap port-changing trick can even be 100% effective against generic massive port scanning attacks. But it's 0% effective against a targeted attack. It depends entirely on the surface area we want to defend against. If we define our protection to work against generic automated bots, then changing the port is an entirely effective solution. If we want to ensure our systems are globally "unbreakable" (whatever that means), then it's a weak security solution. In other words, effectiveness is not absolute; it's relative to the threat model.

It's not possible to inspect all the code we use. There's too much of it changing every second. The idea that developers have the time or ability to manually inspect every line of open-source code they import is an economic fantasy. In an era where frontier AI models like Mythos are finding and chaining 0-days in minutes, human review is simply outpaced. But even if we somehow did it, something would already change by the time you finish reading this paragraph. Everything needs to be reanalyzed because we don't know what shifted. And sometimes, the vulnerability manifests in the parts of the code that DIDN'T change.

By the way, I think you might not be aware that current, "next-gen" security solutions offered by Crowdstrike or SentinelOne are actually old antivirus techniques marketed as something new. EDRs are 'just' log aggregators and routers for signatures to be matched on.

Also, please don't think about programmers as someone immune to attacks, as this is not true at all. The fact that programmers invented a method of installation for programmer tools based on piping curl output directly to bash is direct proof that some programmers have absolutely no idea how security works. Especially web developers. If anything, programmers can be more dangerous than normal users because they assume they are better, and then they make the exact same mistakes as everyone else. They are just plain computer users who need to be defended from their own carelessness.