I have managed to obey the cardinal rule - 'thou shalt not ride' in Mexico or southwards ' at night' so far, having had a few dusk arrivals due to unforseen events. The main reason most people quote is that of being robbed / attacked, but from my daylight riding I can say that from what I have seen then, these are the 5 main reasons not to ride at night - and bandits are not on it as the others will kill you, bandits might not ....
1. Trees lying full across the road (2 so far - both being removed as I came upon them late morning)
2. Cows - these buggers don't care, they must know that they are going to die so why bother looking as they stand or amble VERY slowly across a main road - be it in a village or countryside
3. Dogs - Some must have been reincarnated from the cows, cos they act identically
4. Pot holes big enough to host a toddler's summer paddling pool party for 10 - no, I am not kidding. These suckers were everywhere on the last 30 miles of eastern Honduras, and the first 30 miles of western Nicaragua. I still shudder thinking about them.
5. The locals driving on the wrong side of the road for miles at a time to avoid said potholes.