OK, I'll give you that one. But if kids made a bomb out of a film can and put it on a signpost, either (1) it would blow up the sign post, or (2) it's a dud and doesn't blow up the sign post. If situation (1) happens, no one is going to find the bomb and call it in; they are going to find a broken sign post. Ergo if someone is calling in that they found the bomb, the bomb has already failed.
I'm gonna need a cite for "bombs are in fact quite common." I think there's a difference between fireworks and bombs.
Anyway, we're talking about a FILM CAN here. If you stuffed it full of black powder and put a fuse in it, I suppose you could call it a bomb. The lid would blow off before you got enough pressure for a real explosion; it would be more flash than bang.
But again, if they found the film can with the lid on it, it failed to detonate. Even if it's filled with black powder, it's not going to explode if someone takes the lid off and looks inside.
"But what if there's an electronic thingy with a motion detector that makes it explode when you move it?" Well, now we're way beyond kids making things go boom, aren't we? If it has an electronic trigger it's much more sophisticated than that, we're back to terrorists and the original question of what kind of rational terrorist would blow up a rural road sign?
Sorry, I can appreciate the logic of your thought process, But your argument is built on a faulty premice. Several of them infact. And a lack of real world experience with the subject.
First of, you seem to belive that blackpowder pored into a pipe, with a fuse stuffed into it is all that a "kid" is capable of producing. Speaking candidly, by the time I was 15 I had deployed dozens of what would now be termed IED'd using considerably more powerfull explosives that blackpowder, and an array of ignition devices ranging from both chemical, electric, and mechanical timers. To antitamper devices. Ofcourse, this was back when that sort of thing was considered good clean redneck fun. Don't belive me? that's fine. Google roguescience, or thehive, or AP (acetone peroxide).
Second you seem to believe that a fuse is either on or off. this is not true, a fuse can appear to go out, while infact it is really smouldering. Only to reignite at a really inopportune moment hours or minutes later.
Third, While a film can full of blackpowder would probably only produce singed eyebrows,mild burns.and ruptured eardrums at close range, most any higher order explosive is capable of killing you with only the blast wave at those ranges. If you bothered to google AP, you now know that not only is it super easy to make, by say your average 12yr old. But it's EXTEMELY unstable! As in even if the ignitor fails, it can still explode from shock,age,temperature change, or even just giving it a dirty look.
Fourth, Common sense Is very rarely the guiding principle of LEO's in a situation like that. (I'm not trying to be sarcastic either). Consider, that with the exception of an Andy Griffith style small town sheriff, most police officers would be risking suspension, a reprimand, or job loss by not following SOP for something like that.
Are all those things something you would be willing to risk for the sake of a game where you don't know the people involved, and may or maynot approve of what they are doing in the first place?