Their curse is simply poverty, and perhaps provinciality. These have made an ordinary sort of accident far worse. Due to poverty they did not want to spend the night in an expensive Vheshrame hotel; due to provinciality they had no friends in the city to stay with. So they drove for home. Due to poverty they had little experience with driving, and none at night; due to provinciality, all they had driven before was a heavy farm-wagon, not a light carriage. Due to poverty, the carriage in question was the mayor's, not their own.
And it had been a bad day, and whoever was driving was surely exhausted and perhaps distracted.
So, over the bluff they went.
At least no primes were injured in the accident.