Spitballing here … but I think blowing up a plane with ‘lots of liquid’ … ( I assume that’s why we can’t carry bottles of water on to the plane unless the water is bought ‘plane side’ of security? ) … is old school thinking. It’s one plane and you’re done.
Thinking bigger - I would get a bomb with all that liquid onto the London - Paris Eurostar. Here. it is clear that the authorities are not worried because unlike Airports you might typically travel through .. at the railway stations no such limits seem to be in place.
Further thinking would have me board in Paris - not London, because in Paris they just scan your bag - no need to remove electronics, shoes, belts … so much easier than taking everything out and having to hide all your terrorist toys.
Then when you set your bomb off … you not only take out a train … with probably a lot more casualties … but also destroy a major travel conduit in a single stroke.
or … OR …
Maybe all the bomb detection stuff employed by the railways is so much more sophisticated than the stuff used by Heathrow et al … in which case … hello? Heathrow .. are you there?
or … OR …
Maybe the railway people the French in particular … just know that it’s all just theater and are refusing to take part.
I think I’m going for that last choice … but I really don’t know - it’s just a hunch.
What do you think?