It's a biometric scanner, NOT a fingerprint scanner, does not read fingerprints, just the shape of your finger.
It is much more accurate (higher resolution) with the new touch-point entries than it was with the legacy turnstiles.
It isn't the shape of the finger, but the "shape" of the fingerprint.
"Biometric" just means it is converting some sort of biological identification to a numeric value for comparison. It could be a finger scan, geometry scan (i.e. shape of finger, or really bone structure in the fingers - the old system did that), retina scan, DNA, pheromones, quantum state, etc.
The type of scanners in use DO use a scan of the fingerprint. But it isn't doing a full image comparison of it - that would be slow and require more data. Instead, it is looking at the ridges of the fingerprint, identifying prominent points (the folds, bifurcations, loops, etc.), picking several, and creating a geometric model that is then turned into a numerical value - typically 4-5 digits, depending on tolerance for duplicates. It can do this relatively fast and accurately with a low chance of a false negative (although obviously finger problems will cause issues).
The finger scanners that are becoming prevalent on laptops work very similarly (well, the software used to compare against a stored value does), although instead of an optical sensor, it is a capacitance sensor that you drag your finger across. Think of it as being like a document scanner, one line at a time...
