I'll use the term "threat" for a problem where avoidance and/or submission is a good way of dealing it.

If a tiger is known to live in a particular part of a forest, that is a threat: Avoiding that part of the forest is a good way of dealing with the problem. If I take part in a hunting expedition and I don't do my part because I'm too much of a coward, that is also a threat: If I act as if nothing happened and eat as much food as I want, etc. then my fellow tribespeople will think I'm an obnoxious jerk and I'll be liable to get kicked out. So submission is a good way of dealing with this problem.

If I'm hungry or sleepy or I have homework to do or I need to get a job, those are not threats, even though they have potentially dire consequences: ignoring these problems is not going to make them go away.

Hypothesis: the EEA was full of threats according to my definition; the modern world has fewer such threats. However, we're wired to assume our environment is full of threats. We're also wired to believe that if a problem is a serious one, it's likely a threat. So we're more likely to exhibit the avoidance behavior for serious problems like finding a job than for trivial ones like solving a puzzle.

(I like the idea of co-opting the word "threat" because then you can repeat phrases like "this is not a threat" in your internal monologue to reassure yourself, if you've checked to see if something is a threat and it doesn't seem to be.)