We have decades of research that people ignore warnings — see Vista UAC. People always click continue. There is so much scare ware out there people have become immune.
People became immune to UAC because they saw it everywhere, and were trained that it was safe to ignore. Users don't ignore novel warnings, at least not when they're sufficiently noticeable.
If you try to visit a site in Google Chrome that Google thinks is hosting malware, they pop up a huge red message saying the site will harm your computer. There is a continue link, but... well, I don't have access to any analytics on this, but I would guess not many people visit those sites.
Exactly, if a site that you know is perfectly safe showed that red warning, then you'd probably start ignoring it. UAC would pop up on almost anything you tried to run, making it worthless. The android bootscreen should almost never happen, unless you buy a second hand phone or someone actually hacks your device.
If I receive a warning, I need to find out what it means.
If my primary device is the one displaying the warning, the only way I can find out what it means is to dismiss the warning and then 1) google it or 2) ask someone.
1) doesn't tend to happen outside of the tech bubble. 2) happens way way later, if it happens at all, as the odds of someone you can ask being around when it happens is slim. And more importantly, you need to make a phone call / check your email / do something with social media which is more important than the warning, as the warning can be dismissed and life can go on.
Odds are you forget about it entirely, and remember weeks later to ask a friend about somethingsomething boot warning insecure and then hand over your phone to them to have a look, at which point your friend loses their mind over what's happened, while the phone owner remains unconvinced it's really an issue since everything is still working correctly, and refuses to let their friend rebuild their phone for them as it'll take too long.
Source: happened to my friend's android phone. they still wont let me fix it.
And if they do see the warning? Where will they go to get more information? Will they use their computer? It’s becoming more common for people’s only “computer” being their mobile phone. What do they do when they do get the warning? Do they go to their local non existence “Android store”? Do they ask the clueless CSR from their carrier? Or do they just keep clicking continue like most people do on their computer?
How many people in other context like cars ignore warning lights?
https://source.android.com/security/images/boot_orange.png