at what age do kids stop needing a stroller?

On some parenting decisions, i totally don't judge.  on this one i do.  i took my kids to a theme park today.  At just over 4 1/2, i think they are way to old to be in a stroller.  I'm pretty sure they think so to.  But as always, i noticed many children who appeared to be much older then my own, ridding in strollers.  They were folded in, legs bent at an awkward angle to try & keep from hitting the ground. Isn't at least part of the goal of taking your kids to a place like this, that they tire themselves out?  How do they do that when they are being taxied from one amusement to the next? Of course it should go with out saying, I'm not talking about children with any kind of disabilities.  I got to observe many of these children as there parents pushed them until they got where they were going. At the point, the children simply jumped out of their chariots.  Really??  I can't be the only one who thinks this is nuts!!