They’re sported all over Turkey and in Iraq, people were getting them on all limbs so their family could identify their bodies if they were caught in a VBIED...not everyone is hard-core Islamist..
My point is now made with the arrest of a suspect. Don’t assume things by what the Koran or other writing say when it comes to the modern Islamists. There are multiple levels of conformity in the Muslim world, just as there are in other religions. There’s plenty that are occasional adherents and/or adopt modern trends.