I assume that it's in some way intended to help the police to do a better job of protecting people....and from what I've read further about it, I can sort of see how it might.
Articles I've read in addition to the one posted in the OP:
http://www.heraldscotland.com/news/15558899.More_than_400_000_people[...]
http://www.bbc.com/news/uk-scotland-41335762
The fact that they came up with something like this doesn't disturb me. Without a database, police can still keep records about who they think is vulnerable. Officers can and surely do write comments in police reports about their perceptions that someone is vulnerable in some way or in some particular context. Officers can and do already share people's personal information with other agencies (e.g. child/adult protection services) when they are legally obligated to do so, or when they feel it is a necessary part of fulfilling their duties and there are no laws on the books preventing them from doing so. (They probably sometimes share info even when they shouldn't be doing so, but that's a separate issue -- even though it intersects/relates to this one.)
I'm not surprised police wouldn't tell people they've been added to the databse because its not like they are just randomly gathering information about people who might be vulnerable -- this is only based on information they gather in the course of attending/investigating situations they have been called to that involve the person they identify as vulnerable, and it seems the report they write for the database has to be submitted by the end of their shift on the day it happens so it likely seems to them very much like just an addition to their normal reporting duties. (This requirement to have the vulnerable persons report completed and submitted by the end of shift appears to be repeated in every section of
"Mental Health and Place of Safety: Standard Operating Procedure" published by the Scottish Police -- it came up in the search results for "police scotland vulnerable person database" -- so my guess is the same requirement probably applies to any report they submit to the database about any kind of incident involving any kind of vulnerable person.)
Police are not in the habit of making sure that everyone they talk to in the situations they attend is informed of what has been written about them or what happens to that information. So to me it is understandable that officers might not always recognize or remember that taking the additional step of adding people's names and personal info to a centralized database is any different from regular/traditional police records. (I'm not saying it's okay, just understandable: Officers are responsible for following appropriate protocols that adhere to privacy/information laws, and their superiors are responsible for establishing and explicitly communicating those protocols to the officers in the first place.)
When I first saw the title I thought maybe it was something like how some police departments have a list of autistic people in their jurisdiction.
The police department databases for ASDers are voluntary. (A least, all the ones I've heard of are voluntary -- you or your parent/guardian have to ask to have your name added to the database and you or your parent/guardian/caregiver provides the information about yourself that gets entered.)
I assume that how the voluntary lists of autistic people work is that when the police run your name through their database at the scene of whatever it is they were called to deal with, then your name will come up with information about your autism to help the police interact with you effectively and to avoid terrible things happening as a result of them not understanding your behavior or how to communicate with you.
Would I want my name in any such databases? I actually don't know. I would have reasons for and against, and my answer would change for different contexts.