"government" is a collective noun
"police" is an aggregate noun.
Both “family” and “police” refer to a unit, but we perceive the number of members in each one differently. Greenbaum and Quirk explain that “government” is a collective noun and “police” is an aggregate noun, the latter being a unit with an indefinite number of parts (1990). Other examples that make that distinction clearer are the aggregate nouns
communications, media, and data. Contrast that with examples of collective nouns: committee, team, and jury. Greenbaum and Quirk identify
collective nouns as “ordinarily singular” and
aggregate nouns as “ordinarily plural” (1990). This is why we say “my family is” and “the police are”. Biber, Conrad, and Leech confirm that in
American English collective nouns normally take the singular (2002).
Other aggregate nouns: cattle, swine, clergy, offspring
Some other differences between collective and aggregate nouns:
Use of determiners. We can use indefinite articles with collective nouns but not aggregate nouns: a committee, a team, a jury, a family. (But not: a communications, a media, a clergy, a police.)
Singular and plural forms. In general, we can choose between two forms of a collective noun (team-teams, family-families), but we don’t have this choice with aggregate nouns (one police? two police?)