Student or Learner
I was practicing a grammar workbook, and according to it bunch, streets, and gentlemen are common nouns but shouldn't it be collective noun?
***** NOT A TEACHER *****
To the best of my knowledge, the words "streets" (the plural of "street") and "gentlemen" (the plural of "gentleman") are not considered to be collective nouns.
On the other hand, I believe that you are correct: "bunch" is a collective noun.
I found these two sentences that may interest you:
1. A bunch of flowers was presented to the teachers.
2. A bunch of hooligans were seen on the premises.
The source explains that when the subject noun phrase ("A bunch of flowers") is considered as "one undifferentiated unit," then many native speakers prefer the singular verb.
When the subject noun phrase ("A bunch of hooligans") refers to "a collection of individuals," then many native speakers prefer the plural verb.
Source: Peter Siemund, Varieties of English. (Found in the "books" section of Google.)