I was homeschooled, I can tell you It's not all like that. The Canadian government checked up on us twice a year. We followed the Alberta curriculum (using ADLC), well known for being strong in the maths and sciences. I wrote the same provincials that the other Alberta students did (in a supervised setting at the same time as everyone else.) I found it better prepared me for self motivation and learning on my own. At university I was on the deans list and scored better than 95% of students (exactly what percentile I don't know, but I'm pretty sure it was the highest of all students in the same year of computer science.) I scored 100% in calculus and published three peer reviewed math papers in conjunction with my professor as a first year student. So you can't discriminate across the board like that, even if in general you're probably correct.