Oh they aren't wasting billions at all ...
The average pax spend per head at Heathrow was around £2.80 prior to 9/11 ... nowadays, and particularly since the liquid restrictions were enforced, it's around the £8 mark. Extra £5 per pax, x 70 million per year = £350 million per annum profit at Heathrow alone ... now add Gatwick, Manchester, Stansted, Luton, Edinburgh, Glasgow, Birmingham, Newcastle ...
It's not about "wasting" billions on enhanced security checks, that's more like the money they're making from it every year.