No Credit Check Car Loan

Why can’t I get a car loan? (19 years old good credit no cosigner)?
I’m 19 and I want to get a car loan for $6200 from a private seller. I tried Chase and got denied i haven’t applied yet but state farm said it is doubtful but I don’t understand. I got a credit card specifically to build credit for a car loan. I checked my credit score and it is 744. I’ve been told I need a cosigner but my mom has terrible credit. Is it because of my age? Have I not had credit long enough? Please help
I do have a job I have worked at for 3 years and plan to for the next few years thru school and am being promoted to a supervisor I make about $800 a month not much but for me it is. My credit card limit is 4000 on one and 1500 the other but i have never gone near the limit and pay off the bill almost as soon as i make the charge. Thanks everyone for all the input already
Have you talked to other banks?
Perhaps a community bank or credit union. Chase is one of the big banks that’s really hurting.
You may have better luck talking with a smaller more financially stable bank. And if they deny you, you may be able to get some information from them about why and what you can do to improve your ability to get a loan in the future.