I'm sure we've all seen pax get on the wrong flight, but how many times has that been discovered BEFORE pushback? I'd suggest always. The days of 'Airport' (the film) style grannies flying across the atlantic without a ticket are over, if that was ever possible anyway.
More worrying perhaps is this. On two occasions when an extra pax has been discovered on my flight, everybody has been kicked off the aircraft for a security check - to make sure the errant pax hasn't left anything onboard. On two other occasions it hasn't happened. I must admit that this made me feel a bit uneasy. All were on European majors (although I can't remember which).
In the States they regularly (and still, I believe) ask for volunteers to 'de-plane' over booked flights AFTER boarding if a 'Gold-card VIP type' turns up late. The security checks consist of "Have you taken all your bags, sir?".
I too have stories of sharp stuff getting through security, usually in my wife's handbag
The simple fact is, you are neither significantly safer, nor significantly more at risk than you were 14 months ago - you just have to live with it. Or don't travel.