Has anyone here ever questioned the whole school system?

Sending kids to school has only been the norm for the last 100 years...thats nothing when you look at it in the grand scale. In the UK we send them earlier than ANY other country...at 3 and 4 they are off and spending the greater part of their week away from us...and yet if a Mother considers doing something different then everyone freaks out....and says "oh they won't have any friends" or "who will come to their Birthday Parties?" these seem like tiny thi ngs to worry about compared with the much bigger issue of the fact that our kids are getting indoctrinated by teachers we dont even know! Also getting influenced by kids whose parents we dont know....does anyone have any thoughts?