Ugh, I hate toys with wheels! I only have one shopping cart left and it is for outdoor play only although for me it's a case of the kids being too rough and rowdy with them. I find a lot, if not all, kids go through a hoarding stage at one point or another. I think if the shopping carts are driving you crazy you could try putting them away and taking out pails or buckets or bags as they are pretty similar and might be easier to share. I also agree that I usually let them hoard until they start hoarding too many toys in general or all the really good toys.