I'm pretty sure that whoever named this had a fundamental misconception of what the word "catch" really means.
(It's actually kind of an ironic name i think)
The best example I can think of is a [baseball] catcher. This is a person who stands behind the plate and catches baseballs ... and by "catch" here I mean they actually take possession of the baseball in a glove (or try to).
Fly catcher, catch a cab, catch a cold, catch a fish... you get the idea.
Said another way: they control the thing, in this case, a baseball (or a fish) ... that or: they seek to control the thing by holding it in a glove (or with a hook).
Cow-catchers seek to *not* take possession of the cows (thus the irony).
See the difference?*
If there was a big metal basket on the front of the train that swept the cows up and carried them along w/ the train (at the front) ... well, that would be a cow-catcher. Or like, if there was a patch of sweet grass at the front of the train, and when the cows wandered over to eat it, a big net came down and swept them up and put them into some kind of cow-sized-terrarium, well, that would be a cow-catcher too.
... but not this.
It would be cool if the trains swept the cows up into a big basket and then let them out at the next station. If you had a little extra time on your hands you could go to the station and await the arrival of the next train, and cross your fingers that the cow-catcher was occupied.
Given the current [poor] state of TED talks, I should submit this as a proposed talk and see if I get selected. "TED : Ideas worth spreading".
* it's bullshit is what it is (pun: unintended).