Most don't know. When they find out, most don't believe you're *serious* and that it's *real* that they use aborted fetus to culture the vaccine. I think for a lot it's just too much to process.
I am totally appalled by it, and as a pro-lifer, it certainly is one of the things that changed my mind in the beginning.
I think also, that part of it is that the Catholic Church came out with a statement to the effect that since they aren't STILL aborting babies for it, it's OK until a better option comes along b/c you wouldn't want to be responsible if your kid gave a pregnant woman rubella and that resulted in CRS. On the other hand, if you feel like it makes it look like you support abortion, by all means, follow your conscience... So a lot of people just get it, because the church says it's OK, and you'd have to be really careful to not get those certain vaxes.
I was *really* surprised as a Catholic, when I read that because... Dude. That's so crap. GOD decides what happens to an unborn baby. NOT my kid's vaccination status. ESP since there's no way to tell if the vax even took, whether someone was immune, whether they're carriers of the virus, NOTHING... So I think the whole line of reasoning was an attempt by someone to look like the Church can be reasonable. I also think that the person who wrote the statement for the Church was given some *really* bad information.
Most people that I know that are pro-life DO care about it, but a lot of them aren't sure what to do about it, if anything, and the others just don't get vaxed at all for that PLUS a variety of other reasons.
Anyhow. I think it all boils down to: Most don't believe it could POSSIBLY be true.