That’s fair but one of things that Google’s device backup does encrypt is the messages that are stored on the device (RCS, SMS and MMS), this has been a significant sticking point when it comes to Apple’s device backup service as end-to-end encrypted iMessages and SMS are backed up without end-to-end encryption by default.
I’m not sure the last time you used Android backup and restore was but it has come quite a long way in the last few years. I’ve restored devices from backups and done device transfers and it basically transfers everything now. Apps stay logged in with account credentials and preferences are saved for apps. But yeah you’re right they do expect the majority of data to be backed up in Google services 
however that is pretty similar to Apple’s default implementation of backups.
When iCloud Backup is turned on, the backup includes a copy of the Messages in iCloud encryption key so Apple can help the user recover their messages even if they have lost access to iCloud Keychain and their trusted devices.
I think it’s great that Apple provides end-to-end encrypted backups and encrypts a lot of other services that they offer, however most people don’t enable advanced data protection. I’ve talked to a few Apple fans and they didn’t even know it was an option to enable. Maybe they could implement a more use friendly way to enable it or make it more clear to users that it’s a setting they should enable.