Confusing rule about subject-verb agreement?

Question

I am currently working through "The Blue Book of Grammar and Punctuation" by Jane Straus. In the section on subject-verb agreement the author describes a rule for sentences that begin with "there" or "here" which claims that the true subject in these sentences will follow the verb. In the exercises, there are two sentences where I am supposed to identify the subjects and verbs as well as correct any issues. There is one sentence in particular that is confusing me. The sentence "There's lots of food left" has the subject "lots" and according to the rules given should have the verb "are" but the book states that this is incorrect. The correct verb according to the book is "is". Why is this the case when there is a plural subject?

Answer 1

Food is one of the collective nouns that takes the singular verb even though it refers to a plural. For example: Congress is taking recess next month. Or, at a feast: Look at all the food that is on the table.