Why such criticism?

I saw on facebook the other day where someone mentioned how expensive supplies, school fees, clothes, field trips, etc were each year and they were considering homeschooling. Now, I don't know whether this person was serious or it was more of a 'tongue in cheek' statement, because there was no indication either way. I just kind of shrugged it off.

Out of sheer curiosity, I looked later to see what her comments were. Most people were also complaining about how expensive 'back to school' season can be, but later there were 2 comments that kind of stuck out to me. I'm paraphrasing, but one said something like, 'homeschooling!?!?! Ha Ha Ha, please tell me you aren't serious' and the other was something like, 'ummmm...homeschooling? We need to talk'

I've really had mostly positive or indifferent opinions when we tell people what we do. Some people have questions, and I gladly answer them, because there are varying misconceptions that fly around about it. I have had 1 man from church that questioned me and then hysterically laughed in my face about it while I stood there dumbfounded. In his defense, he did come to me the next time and apologize (Ok, so I think his wife told him to, but it was still nice). I don't really care what he thinks or anybody else, because I don't do it for them. I also know that his laughter and jeering is not all that uncommon either though (even if done more discretely).

I've been at this for 18 months. I'm not an expert in the least, and I don't claim to be (I'm just willing to learn and take things 1 step at a time), but why do people care so much what other people do? Why such criticism of something that most people (I find) are pretty darn ignorant about. I truly don't spend that much time thinking about what other families do, so I think that is where most of my confusion comes in. If you are taking care of your children, pay your bills/taxes, and are a good law abiding citizen, I'm probably going to think that you are doing a darn good job at whatever you decide to do in your own family.