Here in UK, if an officer uses a taser on an individual, he has to fill in a form afterwards in which all the details of the incident are recorded. (A CED Evaluation Form) It's all monitored, to prevent the Police firing tasers all over the place. They aren't used lightly.

I don't really see how any number of armed Police/military can do much against a lone suicide bomber walking along a street or entering a building, looking perfectly normal. Unless one has Intelligence tracking him/her, one wouldn't know the individual was wired-up until the terrible moment when it was detonated, in which event it would be too late.
I read this morning that many concerts due to take place this summer are stipulating no bags except very tiny handbags will be allowed. And to expect huge delays and queues checking into the venues. Unless they frisk everyone thoroughly though, I can't see how it would completely ensure safety.