RHUB WROTE: ---> One accepts, therefore, the apparent grammatical inconsistency on the grounds of custom and practice

... or meaning.

Grammatical Ground Rule # 1. Sec. 1. Page 1.
(like Moses wrote it on the wall.)

RULE ONE:
All rules of grammar are subservient to meaning.

(Wages of sin) one entity (= is) (death) one entity.

Post edit: Oh yeah, I forgot, there's this...

I Got drunk and blew my hard earned wages.
I got drunk and blew my hard earned pay.
In both cases what he blew was his hard earned singular.