Gasoline quality standards are regulated (in the US at least). Also, nobody designs malicious gasoline to intentionally attack your car.

I get the thrust of your argument but I don't think that's a good analogy. Bad fuel can cause physical (including catastrophic) damage to the engine. Bad software cannot do something similar to the phone. At worst you will have to reinstall the OS.

Now I do agree that bad software can wipe all your data or hold it hostage, but Apple currently provides no such guarantees that software downloaded from the App Store won't do that.