Because each site keeps its own roster, in its own spreadsheet, in its own format. Head office consolidates monthly, by which time the questions it could answer are historical.
Cover across sites is impossible: a site short on Thursday cannot see that another has somebody spare, because neither can see the other.
Rosters, attendance and leave sit on one record with a site dimension. Publishing a roster is per site; seeing across them is a filter.
Cover can be offered across sites where skills allow, and the labour cost of a published roster is visible before it is published.
It will not write the roster. It shows availability, skills, cost and gaps; the judgement about who works when stays with the manager.
It also will not override working time rules you configure.
Understaffed shifts show before the day rather than on it.
Labour cost becomes controllable at the point of decision — when the roster is being written — instead of being reported after the month it was incurred.
Yes, with hours attributed to the site worked.
Yes, against the budget for that site.
Yes, subject to approval and skill rules.
Half an hour on your own numbers is usually enough to say whether Nest is the right place to start.