Why do people treat single dads like they are dumb and treat single moms like gold?

i have a 6 year old and a 2 year old and when we go to the doc or to the school or any where people act like i dont know any thing i have had my kids fora little over two years i tought my doughter to walk i am trying to teach her to potty train girls are harder than boys and how come she only has to pay 103.00 a month that dont hardley pay for dypers and wipes what about school clothes she left us she shold have to pay more i thank