Mortgages and car loans are a bit different, but typically if your job history is short, you put higher education in to fill the gap. As long as your degree is for something directly related, they won't mind.

Also, there ARE first time buyer programs for recent grads. Typically it is for people 6 months from graduating till 1 or 2 years after. You get special financing on the basis that you have no solid credit history, but that you do have a degree (or one shortly due) and are employed in a position directly related to your field of study. With minimal history, this will usually net you a decent rate. It's something to fall back on if nothing else is available.