No "rationale" required. You should know this.
This is a well-known fact that was, I think,
first revealed by the late Peter Griffin, Ph.D.
author of The Theory of Blackjack
From p. 184 of The Big Book of Blackjack by Arnold Snyder:
All forms of Late and Early Surrender are worth more as the number of decks increase e.g.
Late Surrender (H17) is worth +0.0.3% in a Single Deck and doubles to +0.0.6% in a Double Deck. In a shoe game it is inflated by 50% to +0.0.9%.
These figures are for Basic Strategy players. Surrender is worth far more to a Card Counter utilizing surrender indices.
Anyone can win or lose, but those whose play is efficacious, Merit credit for good news, and find the adverse less vexatious.