i think they prey on people's um inherent politeness on the phone even with a machine i find people being kind of polite and waiting for it to finish what it has to say and then they feel an obligation to respond even though there's not even a person there
( i ( think ( they ( ( prey ( on ( ( ( people 's ) ( um ( inherent politeness ) ) ) ( on ( the phone ) ) ) ) ) ( even ( with ( ( a ( machine i ) ) ( find ( people ( ( ( being ( ( kind of ) polite ) ) and ) ( ( waiting ( for it ) ) ( to ( finish ( what ( ( ( it ( has ( to say ) ) ) and ) ( then ( they ( feel ( ( an obligation ) ( to ( respond ( even ( though ( there ( ( ( 's not ) ( even ( a person ) ) ) there ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) )
(ROOT (S (NP (FW i)) (VP (VBP think) (SBAR (S (NP (PRP they)) (VP (VBP prey) (PP (IN on) (NP (NP (NP (NNS people) (POS 's)) (JJ um) (JJ inherent) (NNS politeness)) (PP (IN on) (NP (DT the) (NN phone))))) (SBAR (RB even) (IN with) (S (NP (DT a) (NN machine) (NN i)) (VP (VBP find) (S (NP (NNS people)) (VP (VP (VBG being) (VP (ADVP (NN kind) (IN of)) (VBN polite))) (CC and) (VP (VBG waiting) (PP (IN for) (NP (PRP it))) (S (VP (TO to) (VP (VB finish) (SBAR (WHNP (WP what)) (S (S (NP (PRP it)) (VP (VBZ has) (S (VP (TO to) (VP (VB say)))))) (CC and) (S (ADVP (RB then)) (NP (PRP they)) (VP (VBP feel) (S (NP (DT an) (NN obligation)) (VP (TO to) (VP (VB respond) (SBAR (RB even) (IN though) (S (NP (EX there)) (VP (VBZ 's) (RB not) (NP (RB even) (DT a) (NN person)) (ADVP (RB there)))))))))))))))))))))))))))
People prefer listening to recorded messages on the telephone instead of talking to other people. 
( People ( ( prefer ( ( ( listening ( to ( ( recorded messages ) ( on ( the telephone ) ) ) ) ) ( instead of ) ) ( talking ( to ( other people ) ) ) ) ) . ) )
(ROOT (S (NP (NNS People)) (VP (VBP prefer) (S (VP (VP (VBG listening) (PP (TO to) (NP (NP (VBN recorded) (NNS messages)) (PP (IN on) (NP (DT the) (NN telephone)))))) (CONJP (RB instead) (IN of)) (VP (VBG talking) (PP (TO to) (NP (JJ other) (NNS people))))))) (. .)))