Why do people say, hijab is sexist?

When looking at people with no hijab, they look like people of no value like prostitutes. Men like to look at them, so when men say it do they wan tto see women, when women say it, why? also looking at a womens perspective, arent they naturally shy, also doesnt the hijab make a women more precoius then a person who is revealing. answer my 2 questions which is marked by question marks btw.