Most hardware companies don’t care in the slightest about software quality. To them, software is just another line item on the Bill Of Materials, like a bolt or piece of sheet metal. You either have some overworked intern who knows C cobble something together that barely works or you buy it from the least expensive supplier. When the build is ramping, at the end of the assembly line somebody is going to flash something on the device, and they are not going to stop the line to worry about a security hole.

I think your question is wrong, it should be: Is it realistic to trust any company to build completely secure software?

I don't see your point about Apple, unless you're being sarcastic for comedic effect. Apple release software with security flaws too. In fact a zero-click security vulnerability present in the Apple email client was posted on this very page only three days ago[1].

[1]: https://news.ycombinator.com/item?id=26664714

This wasn't about the security of their "software", as in the thing that's running on your device. This was about their backend security. That's a much, much tougher call to make.

iOS exploits are cheaper than Android exploits because iOS exploits are so plentiful in comparison[1].

[1] https://www.cyberscoop.com/ios-zero-day-zerodium-high-supply...