Many companies have policies that will pay for your lunch when you are out of town on business for them. I believe your confusion comes from the fact that so many companies have policies like that, then we just expect all of them to provide that as well. Also, some companies will only pay for those meals or per diem costs when you are out of town for at least a night. Being only 30 miles out of town would not normally be enough to kick in those requirements.
No your employer is not required to pay for your offsite lunch unless there is a written company policy.
Take a cooler - toss your lunch in it, put it in the care and on lunch go eat outside. Tada - problem solved. Really dude - it's one day for pete sake it won't kill you.