Building penetration has more to do with the frequency band T-mobile uses. ATT and Verizon use lower frequencies (around 700 MHz if I recall) than T-Mobile (1700 MHz). Lower frequncies are better at penetrating through building materials. Basically att and Verizon paid more and were earlier to the party to register the lower frequencies with the FCC.
Toy story midway building is a total dead zone for T-Mobile. There are a few others as well I can't recall at the moment.
Bottom line, overall coverage is ok in the parks, the shortfall is T-Mobiles carrier frequency when within a structure.