We could do that, but it's always safe to use `id` on the record, because ActiveRecord::AttributeMethods::PrimaryKey [defines the `id` method to always read/write the primary key](https://github.com/rails/rails/blob/master/activerecord/lib/active_record/attribute_methods/primary_key.rb#L16), and then actually [aliases a method with the primary key name to the `id` method](https://github.com/rails/rails/blob/master/activerecord/lib/active_record/attribute_methods/primary_key.rb#L50).  Obviously, this means that if we use a custom primary key name, we can't use an `id` column name at all, but that's a separate issue.