Show a before/after: "Previously I used string constants for order status. Now I use a backed enum, which gives me type safety, autocomplete, and easy database serialisation."
Good answers explain that typed properties (PHP 7.4+) eliminate the need for manual type checks in setters and make code self-documenting. Enums (PHP 8.1) replace magic strings and class constants with proper type-safe values. Strong candidates give concrete examples: enums for status fields, typed properties in DTOs, and discuss how both improve IDE support and static analysis.
Tests awareness of modern PHP. Candidates stuck on PHP 5.x patterns are a concern. Look for practical understanding, not just feature awareness.