> [0] International flights connecting in Heathrow have to go through security again, even though they've already gone through security at their original point of departure.

That's not terribly uncommon, or particularly unreasonable -- security standards and implementation vary significantly in different countries, and in as much as security screening is useful, you'd want to redo the screening with the local standards, unless you have separate facilities for international flights arriving from countries you know do a good job and other countries, but the customs/passport control section is probably shared among all international arrivals.