Dropping "it" in America

Before I embraced descriptive grammar it would really grind my gears when I heard, usually from someone with a US American accent, phrases like "I hate when that happens". "Hate is a transitive verb!" I would yell.

(To my knowledge it's not normal to drop it in "UK English".)

However, these days I'm more mellow. My left eye twitches but I pinch myself and remember that language evolves.

Which leads me to my questions. I've seen the dummy object eroded from phrases involving love

• I love when you give me a kiss
  — Ordinary Alphabet: Poems by an ordinary girl, p. 107, Michelle McNair, Bloomington (Indiana): Author House.

• I love when she screams to the audience
  — Tell Them That I Love Them: A Story of Grace and Redemption, p. 206, Angela Sanders, Euclid (Ohio): Sandstorm Publishing.

and hate

• I hate when that happens
  — Letters to My Sister, p. 61, Maxine Oliveres, Pennsylvania (Pittsburgh): Red Lead Press

• I hate when people try to take advantage of me
  — If You Could See What I See, p. 93, Cathy Limb, New York (New York): Kensington Publishing Crop.

in "American English". Is it only dropped before a conjunction, or is it OK to drop it at other times? Is it only love and hate where it gets dropped, or are there other verbs that lose the dummy pronoun?

"I hate when that happens" is a transitive usage of hate. The object is the clause "when that happens".

Compare "I know he is lying", where "he is lying" is the object of the transitive know. Also "People say Roberta Flack is a great singer", where "Roberta Flack is a great singer" is the object of the transitive say.