When did "kids" activities get so expensive?

Was looking to take my family to liberty science center b/c the have a Curious George exhibit my toddler daughter might like. 3 tickets is just over $100 dollars. Same thing for the sesame street play area at the american dream mall ... I went to the Lego store in Atlanta and it was also over 20 per person. No discounts for adults or children (I remember it used to be one or the other usually). When did it get normal for family oriented experiences to be so expensive? I seriously have trouble finding things to do indoors with my family around here that don't also involve shopping or heavy entrance fees. What are some good alternatives in the area?