Re: Security expectations
So in England TFL carries about 4 million passengers a day on the rail about 2.75 million per day in 2010... so that seems unlikely that you could search everyone (or even a useful percentage)- not to forget many stations aren't manned. But pretending it was possible to check everyone or even a useful percentage of everyone.
What rules would you have around what you can take onto a train / tube / bus given I've seen people with more or less anything you can reasonably imagine fitting onto such a piece of transport carried by up to two people. Not limited to a kitchen sink, bicycles, monitors, wide screen tvs, laptops, food, people with a weekly shop, power tools, knife sets, a butane canister, wheelchairs, prams, children's toys and clothes.
That's just shit recently. So even if it was possible to search everyone in a timely and useful fashion how would you decide what you could and couldn't carry. The general problem with security is unless you can apply it to every single person all the time then your security will fail. So forget spot checks, they just keep honest people honest.