Why are all organized runs so early??

Just why. This Sunday, half marathon at 8:30 am, starting on the middle of a bridge over the Danube (where it's 4 degrees colder than anywhere else). Closing time: 2h30m (11 am). Why not start at 12 and let people sleep? I just don't get it.

One month: Full Marathon starting at 9 am,

Just why is this a thing in running?