Your instincts are good, little one. They'ze be some cooperatin' on the victims part to stay put until they tired of these guys.
Did you really just write that? Got any evidence to back that up?
No, that’s not true. People who have been kidnapped like that are usually confined, chained, tied up, etc. unless their kidnapper wants to take them out to “play” with them. There is also usually a complicit person around who knows about the situation and watches the kidnapped person (as in the California case, the kidnapper had a wife who actually helped him, and the same was true in a few other recent long-term kidnappings, too, in England and Germany).
Some of them develop “Stockholm Syndrome,” where they feel completely dependent upon their captor, which is the result of the fact that they actually are completely dependent upon him and by not rebelling against him they feel they are protecting themselves.
In this case, I would say the girls had probably been held in the equivalent of solitary confinement much of the time and may actually not have known where they were being held or if anyone around would or could help them. Furthermore, who knows what he told them.
Children are often told that their parents have abandoned them, and young adults are usually degraded to such an extent that they no longer feel powerful enough even to escape. The girl who did escape even had to be told by the neighbor how to kick out the screen door. Thank God the neighbor took her seriously!
I would suspect that the kidnappers had gotten overconfident and the girls, or at least one of them, finally saw her chance and took it.