Like I said, it is pretty sad. The mistaken identity usually occurs in the winter when they have their winter pelt, at least look a tad larger. Most folks don't realize there is a canine that can climb trees with ease, so that bahavioral trait throws people. Some folks also think they have more of a feline gait than a canine gait.
Beyond that, I am clueless as to how folks make the mistake. But I can tell you that within the last month, this very problem set off a media storm here in Texas. If you want a pretty decent read (and get really mad, hindsight 20/20 is great) about this being a problem, read the book "Beast in the Garden". It discusses how the mountain lion situation got set up for someone to get killed in Boulder, Co. One of the issues was that people called wolf (lack of better analogy) so often on yellow labs and grey foxes being mountain lions, that officials started ignoring the calls and just assuming it was another misidentification.
Heck, I'm floored how often bobcats are called mountain lion, but at least then they are in the same family.
And yes, I spend any free time researching Alaska for the upcoming trip
"Conservation of our resources is the fundamental question before this nation, and that our first and greatest task is to set our house in order and begin to live within our means."--Theodore Roosevelt, 1909