Some hotels take scans or photos of guest info so hotel employees can identify the person, perhaps even by name, at a later point during the stay. To "personalize" the stay is one purpose of such collection, but it is (relative to other purposes mentioned) the least frequent purpose to collect guest photo/passport data.
Originally Posted by
travelinmanS
What would you worry about? The info is simply submitted to the local police as required by law.
Passport data of hotel guests has been lifted and misused by non-state criminal actors and even by some state actors. Such collection of guest passport info facilitates: the creation of fraudulent documents; the forging of documents; and the fraudulent or otherwise illegitimate use of real documents or of data thereon.