The OP isn’t (knowingly) asking about a Bulgaria Security Charge. The OP is asking about a Lougne Access Charge which, by the way, it specifically states on their receipt.

But you’re right. Everyone should double check on ITA Matrix the taxes and charges they’ve paid, cross match them with the charges they found on their receipt (ensuring the right fare codes match etc!) and just accept a security charge might be called a lounge access charge 😉

OP; don’t be put off by not checking such things. It is what this forum is for. I find it an interesting choice of words for a security charge!