I'm not exactly sure that's the case. In previous episodes, before the whole deal that occured between J and K, Kate CLEARLY said that they don't keep the cameras around them 24/7. She feels stifled when the cameras are around and at most they keep them around a couple hours a day. The show was given to them. They didn't ask for it.
You can't say for sure [and neither can I] that they're just doing it for the money unless you know them personally. This TV show, like I said, was gifted. They were, if you recall, originally found by TLC and they did one of those one hour specials on them. Afterwards, they proposed the TV show. In these times, however, I think there was the matter of just doing it for the publicity and I think that's more for Kate's case than Jon's, who I think is trying to avoid the tabloids as much as possible.
If you think about it, people are posting photos in official magazines before they happen on TV. The paparazzi follow this family now that they have the opportunity and "a juicy story".
And as for the twins, Mady carries the most attitude and I know plenty of girls who act the same exact way [and of her age group]. Cara's more understanding and rarely ever shows attitude. I think there's more now because they're undergoing extreme changes in the family