Chrome (OS)'s security model is a lot better, and compared to Android it was designed more in-house. Android was an acquisition and has more legacy design baggage (though of course the vast majority of the code has been written by Google at this point).
The latest junk even made it into Android 4.1 devices for security updates. But that is neither here nor there, the fact that we have 4.1 devices is a problem.
But, iOS's superiority (a) derives in significant part from Apple's total control over the hardware platform†, and (b) comes at the cost of a lot of user control tradeoffs that nerds like us tend to hate.
Really, to suggest that Android's security is at parity with Apple's, you'd have to be arguing that Apple does a terrible job at exploiting their inherent advantages of control over hardware and control over what's allowed to run on the platform. Apple does not do a terrible job at those things.
† Yes, Google controls some of their hardware, but they have an ongoing support requirement for a lot of hardware they have no control over at all, and will have that requirement forever, which limits their options.
Android development feels a lot like current web development plans, where things are released, and not a lot of thought is given to backward compatibility and backporting security. Google needs to tighten those reins a bit, either by pushing handset developers forward faster and/or giving reasonable support for older devices themselves.
Today, 8 years later, my Mom and Dad think Windows is a "secure" system as they haven't had any issues for long enough that their opinion of it has changed.
The final leg of this journey will be when Windows + Windows Defender is all you need to keep your system secure. Basically once there isn't a market for add-on security products because the base product is "good enough."
I'm curious why you mention Google though, their security record on Android is a lot worse than either Windows phone or IOS. In many ways I feel like they are exactly Windows in 2003 with regard to "its secure if you use our APIs" kind of security. Would love to hear your thoughts on that.