In Apple's case, starting with macOS Tahoe, Filevault saves your recovery key to your iCloud Keychain [0]. iCloud Keychain is end-to-end encrypted, and so Apple doesn't have access to the key.

As a US company, it's certainly true that given a court order Apple would have to provide these keys to law enforcement. That's why getting the architecture right is so important. Also check out iCloud Advanced Data Protection for similar protections over the rest of your iCloud data.

[0] https://sixcolors.com/post/2025/09/filevault-on-macos-tahoe-...