This raises a few questions. Also need to consider the possibility that a smart pede designed or modified their building to resist the heat.

Was there a non-health-related reason for banning asbestos?

Were corners cut in construction of the buildings or in the manufacturing of the materials used? Grenfell Tower. Is it even possible to add enough fire retardant to plastic to prevent an "open air" flashover?

This is so Spy vs Spy, but could a tanker dump an accelerant that would not cause a big telltale fireball like Hollywood gasoline explosions? Liquid O2?