...must chime in...

first of all, not all drive throughs are busy, bumper to bumper, whatever, except during peak hours ( friday pm, late)

second, I find it absolutely ludicrous in this day and age when businesses don't support cyclists. If it were me, I'd have a little chat with the manager, and possible take my business elsewhere, mainly to a business that did support cycling.

FWIW, I bank at a local Wells Fargo, use my bike at the drive up all the time, and have never had a problem. They let me bring it in the lobby too.