Bc I want to win the Guest Pass since I have a lot of gold and green to spend, but I always do the Diner jobs and I always get 10 green points -.-"

WeeWorld has not made an official statement regarding how Jobs prizes are selected, but it would seem that lower-ranking Jobs result in lesser prizes, as you have seen. This was likely done on purpose in order to encourage users to spend more time advancing their rank.

Because of this, you have a higher chance of winning a VIP Guest Pass by completing higher-ranking Jobs.