E.Z.
Hi there.
I do not have the same problem, whereas we never even get to have anyone over.
Like one of the other moms said; we give out our phone number-but never get anyone elses, and then noone calls.
My son had ONE playdate in Kindergarten, and none in 1st grade. (he is currently in 1st grade) He has a lot of friends at school, but never see anyone after school unless we stay after school and play with whoever is still on the playground.
I'd have to say that what you are explaining seems weird to me, as a parent I'd love to return the favor - why not?
Makes you wonder-are they really that busy? Do they work full time?
If you are driving other peoples kids - I'd ask if they could pick up your son/daughter one day and take him/her home until you come pick them up. (if you are comfortable with someone else driving your child) Kind of like instigating a playdate.
It should be equal if you are doing pick ups and stay afters.
If they don't, I'd say you are being used, and that is not fair.
Even if they work, they should at the very least offer to make a playdate on the weekend, even if just for a few hours. As the kids get older, they'll figure out how to contact each other, and if they live close to each other, even walk home to each other.
In the meantime, why not ask the parent when they come to pick up if it would be allright if your son/daughter came home with them the following....whatever day. At that moment they should at least feel guilty enough to agree!!!!!
Good Luck!