As far as I know, Android VPN API does not expose setting up IPSec or IKEv2, it just creates a TUN device and forwards all the IP packets to you, it is upto you

As far as I know, Android VPN API does not expose setting up IPSec or IKEv2, it just creates a TUN device and forwards all the IP packets to you, it is upto you to handle it, therefore most devs I guess just sends the packet without encrypting. This does not mean they should be insensitive, but it is not suprising the most people have chosen the easy way. I guess iOS allows setting IPSec and IKEv2 VPN profiles, but did not try it. And, to actually create a TUN-device like functionality, it requires manual permisson from Apple, as OpenVPN did.