Why does it seem to be much harder to hit a 4-outs boat draw than it does a 3-outs pair draw

Been playing for 10+ years and it seems so much harder to hit a 4-outs boat draw than it does to hit a 3-outs pair draw. Often I (and others) go to the turn or river with a 3-outs A-high and hit an Ace but rarely (it seems) do we go to the turn or river with 2-pair and hit a boat. Why is that? Am I alone on this?? Please tell me I'm not crazy!! LOL See example and tell me how more likely I was to hit a K or Q on the turn than my opponent an Ace. As for the river...does a boat draw loose a lot of value if  the turn card is an overcard to the boat draw and even more so if it's an Ace?  If so, does this mean I should have folded to the turn bet?  Thanks!