I always thought it was weird that you could keep an iPad packed in your carry on but a laptop had to be scanned separately even if it was a similar size to an iPad.
The laptop gets pulled out and placed in a bucket. The tablet and phone stay in luggage.
It's all so inconsistent, it makes you wonder if any of the security agencies half any clue at all.
I my case, all they see is a huge collection of wires and small devices, so all of that needs to be put on separate shelves and scanned again.
Of course, the really maddening part is the inconsistency. I use TSA Pre-check when possible, so I'm accustomed to not taking off my shoes, unpacking my bags, etc. It's a giant hassle when I'm flying abroad and the rules change. Especially since the rules change arbitrarily - I've passed through Edinburgh a few times over the past 2 years and sometimes the laptop comes out, sometimes it stays in the bag.
On the other hand, if routinely they can't properly scan it and have to deal with delay, they will instruct people to take it out of the bag.
In the end it still is security theatre so it doesn't have to make sense as long as it looks convincing enough.
I fly SGP, SGN, BKK, TPE. SGN did have me remove my shoes last time I flew though, which was a first.
It was just really bizarre to me.
One time I've had to take out my tablets, out of my bag and out of their case even.
Probably not very transparent to x-rays
And metal in laptops is often varying thickness (either due to the design, or poor manufacturing tolerance), hence the concerns that organic explosives can be hidden in their "xray shadow".