It would be pretty straight forward to rig a pager to run off of one battery while the other is an explosive charge made to look like the actual battery.
It seems the pager bombs only killed the users. But they also harmed a lot of people around them.
I've had my stuff tested for explosives, and it did not involve turning anything on.
Not every airport does exactly the same thing. Some do multiple things. I don't think it was even implied that all airports are exactly the same. My point was about density of battery and explosive material, and not about these "other ways."
For that matter, the xrays and other visualization scans also show the density similarities between batteries and explosives. And that density was the entirety of my point.