It's pretty rudimentary
It is that and so is the electronic turnstlye.

The only known fairly accurate way is the magnet token ie you're given a magnetic token and a beep sounds when the token is passed or the person holding the token has passed the loop system,this particular is extremely usefull in building security ie the token is still with the person till they leave the exit,this then counts how many people have entered and how many people have left and on computer the security can check how many people are still in the building in the event of a fire or bomb scare?

But again it still fails on a true count via a person on returning visits to the building but on a daily basis its flawless.



Bit like the clothes shop where they have security tag badges on the clothes.