Both of my sisters dont have children, I have 4. We dont have a paticularly close relationship with eachother but we still do cards and gifts for special occasions, so me and DH buy gifts from us to and the kids for each of them (and for the partner of the sister in a relationship) and then they are buying gifts for us and for each of the 4 kids.
They both go over the top on presents to the kids, I dont know why, its greatly appreciated but is not asked for or expected.
AIBU to not have been buying them gifts for their birthday/christmas equal to the amount they spend overall on us and our children?