SanFran wants to know who is attending concerts:

sfgov2.org

Notice of Hearing on Proposed Adoption of Rules Related to Security at Places of Entertainment and One Time Events:
…
3. All occupants of the premises shall be ID Scanned (including patrons, promoters, and performers, etc.). ID scanning data shall be maintained on a data storage system for no less than 15 days and shall be made available to local law enforcement upon request.

4. High visibility cameras shall be located at each entrance and exit point of the premises. Said cameras shall maintain a recorded data base for no less than fifteen (15 days) and made available to local law enforcement upon request.

5. The exterior of the premises shall be equipped with lighting of sufficient power to illuminate and make easily discernible the appearance and conduct of all persons on or about the premises. Additionally, the position of such lighting shall not disturb the normal privacy and use of any neighboring residences.