I can understand you thinking that and there's probably some truth to it but do I consider Android and iOS compromised with government backdoors? No. What do I base this on? The lucrative black market for Android/iOS 0days.
And who's buying them? Generally, state actors, directly or indirectly. There is an entire ecosystem of Israeli "security" companies that exist to farm out these exploits. This is a big part of why Israel is such a key component of the American national security infrastructure. Israel is largely beyond the jurisdiction of American courts and any kind of direct scrutiny by the government.
It's a bit like how the US isn't (technically) allowed to spy on US citizens. How do they get around this? By farming out such activities to allied intelligence services, particularly Five Eyes members.
This entire ecosystem and marketplace just wouldn't exist if Android or iOS were fully backdoored.
I see your point, but this could also mean that the backdoors are there, just only a few organisations know it (let's say US army) and then they get found and found again