Qwertyplop
You just don't get it, so I'll say it one more time.
The UK authorities and airport management, in combination, provide an experience that is poor compared to the alternatives for travellers changing planes.
Many, many people like me avoid changing flights in your country because of this.
This is costing your economy a substantial amount of money and giving other contries airlines competitive advantage.
I don't know why you huff and puff about the supremacy of the state controls over commerce, because the other countries are rigorous too, in fact the UK does not have a stellar reputation abroad for it's ability to control it's borders.
My point is simply that people like me can shop around for where we change flights and we do.
You can jump up and down and wave your fists and shout until you are red in the face and it will do no good, because we can't hear or see you from 37000 feet as we bypass your tawdry airports and long queus.