The Glass Bridge (Spoilers)

How was the glass bridge shattering after they made it across fair? The Front Man seemed very passionate about the games being fair, but how the fuck was that fair to have the glass bridge shatter and cut everyone up that made it across? That could've potentially killed all of them and they'd be no one left to play the game.

It made the final 3 kind of bullshit cause the girl was wounded from that glass pretty badly and it essentially killed her, even though she fairly made it across the bridge.