Lizzie, do a poll now of children. I think we would be surprised at where they think meat and milk comes from ( other than supermarkets of course).
Yes, the ignorance is still out there, but not because the info is not available to them on tv, on the Internet and indeed everywhere. But now in 2019, unlike the 1930's (which my Eastend mum used to refer to on this type of subject) it is probably due to many parents still being reluctant to inform their little darlings about one of the facts of life; us humans eat living things, like those cute little lambs!!
As Andy touches on there are young children who understand the truth, but I must say I would have been that little girl in 1958 who would not have known that grissly fact. I was a very a emotional kid, and still am as an adult, who would have cried her eyes out if I was told things like that. In fact it was in about 1960 when I first saw on TV a lion killing some young, helpless, and cute animal. My mum took ages to calm me down and, with much love, explain that was nature; it was the way of life