Implying that the Chinese are any more likely to be listening to the world's communications through their phones than the Americans are likely to be through their phones is farcical.
I'm not saying it can't be both. But American companies already own the mobile operating system space. If we're owned by the US, it's likely there. And those companies are most likely but playing ball with the Chinese as nicely as they ate with the Americans. And that's why backdoors built into Chinese hardware for Chinese spies seems at least plausible to me.