My dress code is green for air travel and restaurants.
I pay for the service, I don't dress to impress the vendor.
If the steak dinner was free in exchange for me dressing up, I might do it...but the cut and preparation of the meat would have to be really, really good for me to consider it...Sullivans, Mortons, or Ruth's Chris minimum.
At work and for clients, I don't begrudge a monkey suit...they give me the green.
If I am footing the bill, I dress as I please. If the vendor has an issue with it, I find another vendor.