Wow.
Amazing that people are still going through, despite everyone knowing what danger there is and what precautions to take.
USUALLY, though not always, it's not a local/someone familiar with the area. Not always though. In more recent times, there has been growth in the sports (snowmobiling/ice fishing) as more people get new toys to play with and they weren't raised on how/what to look for.
Ice is finicky stuff. Sometimes a lake can be thick with ice in warmer temps (as in closer to the freezing point) and thinner when it's colder because of the snow cover acting as an insulator. People learn to read the conditions over time and that means being familiar with any given lake.
Yea there are generalities like 'no snow + 30deg below zero for a month = thick ice' but it's always a risk going out there no matter what because of currents, past snow cover etc. People watch 'Ice Road Truckers' or whatever and think they understand how it all works, but it isn't like that at all. Out here in the Mohave, (I live in AZ now) people go out in the desert all the time and end up dead because they don't bring any water or they think their brand new $50,000 4x4 can't get stuck because it's a $50,000 4x4.