The answer has to do with the way the house edge is defined. The astute reader may wonder why the player should accept a win of 1,300, at a house edge of 4.97%, rather than parlay, when the house edge in single-zero roulette is 2.70%. Thus, I would do that rather than accept a win of 1,275 or less.
By parlaying a first win on zero himself, the player can achieve a win for two consecutive zeros of 1,296 to 1.
