If children are properly brought up, they will go because their parents tell them to. In addition, if the RE program is well done, they will *want* to go because it's interesting and fun.
I really have no resonance with this issue, because our family does an hour or more of Bible and catechism study every day. In addition, the older children listen to religious instruction tapes, because they want to. We like to learn; we like to learn about our faith.
I'm convinced that the Catholic Church has it backwards:
We teach children and play with adults, when we ought to be playing more with children, and teaching adults.