That being said, I also have an Xposed module to get rid of the confirmation prompt entirely (I use Tasker to enable the VPN automatically when my phone connects to unsecured wifi networks).
I can't speak to how Apple does it, so maybe it's just an OpenVPN vs IPsec thing. If you setup your own IPsec VPN you could possibly have it activated automatically. There was a post on HN a few months ago with a script to basically setup an IPsec VPN automatically for you.
Anyone know of a portable, travel wifi router that supports VPN and fails closed?
As a result of this bugginess, I'm no longer willing to use untrusted wi-fi networks even with VPN. It's really too bad that Apple is not fixing this, because it renders the Connect on Demand feature useless from a security point of view, and it nullifies the functionality of Cloak. Cloak is otherwise an awesome app and service, and it's not their fault as they can't control this code.