Why do consultancies only require people who have cars?

i have a diploma,i work at a college as an assistant PRO and not earning enough to even get a license let alone buy a car and im on fixed term contract.the college has been stagnant for the past 5 years,and i have no hope of ever getting an increament..it does not accomodate ambitious young woman like, me so please explain to me why am i not good enough with my experience and my qualification to get a good paying job so that i get myself a car and further my studies and excell in something that im passionate about.