As much abuse as the TSA get, I've always found them to be friendly and courteous. Some UK one's have some bizarre megalomaniacal complex.
I find that too. I think it’s the difference between a single organisation whose standards apply to a whole country, against having lots of little fiefdoms who can implement nonsensical rules with no justification. Also, in the US, aircraft crew are in some respects treated as part of the solution rather than part of the problem. In the early days, it was pretty bad in the ’States but they do seem to have learnt on the job and if you don’t go looking for trouble, I find the process is about as swift and painless as it could be made.
The UK is a mess, with ID systems that don’t talk to each other, non-existent staff training in some instances and a significant number of personnel with what I can only call ‘attitude’. Treating people (99.9999% of which are NOT terrorists) rudely and arrogantly does not help in the detection of the genuine article, in fact it provides cover and distraction for them to slip through unnoticed.