I'm just posting out of interest to see what other people's views are on this.
I don't drive, but a lot of my dc's friends' parents do. My dc's are often invited back to other houses after school, for tea + sometimes sleepovers. Their dc's often come back to us too, but generally their parents insist on either driving my dc's back after a playdate, + picking up their dc's from my house.
Now although I don't drive + nor does my dh, we don't rely on others + get around very easily on public transport + take a lot of taxis. Basically we use the money that people would normally spend on their car, on transport.
We don't want people to feel obliged to do all the running, so I always offer to taxi their dc's back to them, or to come + pick mine up by taxi, (or bus in the daytime). They respond as if I've suggested going to the moon + back! It's, "Oh don't be so silly, of course you're not taxiing, it's no problem at all for us to drop off/pick up!" A few weeks ago my friend actually laughed, rolled her eyes + said, "Oh, what are you like?!!"
Now I know they mean well, but does the offer of a taxi seem so silly? Surely at times it would help the other parent if they were busy themselves, (there's no financial issue with us by the way, I'm just very used to taxiing around + think nothing of it!)