Regarding your traffic example, there's a striking difference in the behavior between young adults who want to signal (and sometimes go through with) committing suicide and older adults who actually want to die.
According to a report released by the American Association of Suicidology1, there are 25 attempts at suicide for every one success.
In young people (aged 15 - 24), the odds are between 100 and 200 to 1 against. The elderly seem a lot more successful at 4:1.
For someone who actually wants to die in the EEA, suicide seems trivially easy. Pick a direction and start walking, if you find water you can drown; if you don't find water, you're dead anyways. If you find animals, some of them want to kill you; if you don't find animals, the environment probably wants to kill you. If you hurt yourself in any way (cutting self, fall from height, eating poisonous food, etc) then you can easily die even if you change your mind and even if somebody can find you (which they won't if you just walked for a day).
For young adults who want to signal suicide, I imagine things would look relatively similar to modern life (minus guns). Jump off high things, eat a lot of things that 'should kill you', self-harm, etc. By a factor of 200:1, the goal of suicide isn't to succeed, it's to make a credible threat (and arguably, that 1-in-200 just messes up). You can make that threat just as easily in the EEA. You don't have to beat your own survival instinct for suicide to be successful, you just have to beat your tribesmates in chicken.
Jumping off a high place in the EEA seems a lot more likely to leave you irreparably handicapped than it is in the present. Possibly eating harmful things as well, depending on what harmful things are available.
I sometimes have thoughts of suicide. That does not mean I would ever come within a mile of committing the act of suicide. But my brain does simulate it; though I do try to always reduce such thoughts.
But what I have noticed is that 'suicide' is triggered in my mind whenever I think of some embarrassing event, real or imagined. Or an event in which I'm obviously a low-status actor. This leads me to think that suicide might be a high-status move, in the sense that its goal is to recover status after some event which caused a big drop in status. Consider the following instances when suicide is often considered: