The reason they're grinning is that they finally got a job and have their uniforms.
I wonder if they will be still grinning when they find out how little they are paid and how many hours they will be expected to work.
The last flight I had with Jetstar the crew were chewing on chocolates during boarding in the front galley.
As the Jetstar ad goes "You get what you paid for"
The only problem I have is that they impact on mainline flying and on my choice of flights to go home on.