It avoids detection by being hypothetical and imaginary, meaning that it exists purely on the meta layer where the scanners cannot reach.

I would guess the people targeted with these devices do not travel a lot via commercial airlines. Or at least do not carry phones that can be confiscated and scanned.

most likely because the headline is false.

For the hezbollah attack, it wasnt detectable because they used a very small amount and they used PTEN which is harder to detect than other explosives. Even still there is a lot of speculation online that they might have detonated earlier than planned due to being discovered