It's built into Android as well, typically accessible from the Setup/Security & Screen Lock menu. However, it is not the default in Android, the boot-up sequence is a bit hokey when you turn it on, it really slows down access to the underlying storage, and the keys aren't stored securely. Also, most telco's load crapware onto your Android phone that cannot be removed and that often includes backing up to the telco or phone vendor... and those backups are not even remotely secure.
On Apple devices the encryption keys are stored on a secure chip, the encryption is non-optional, and telcos can't insert crapware onto the device to de-secure it.
The only issue with Apple devices is that if you use iCloud backups, the iCloud backup is accessible to Apple with a warrant. They could fix that too, and probably will at some point. Apple also usually closes security holes relatively quickly, which is why the credit card companies and banks prefer that you use an iOS device for commerce.