The fast-food companies, perhaps sincerely, say they exclude nonmotorists because they are concerned about safety. But such excuses fail to account for a larger problem. Even if pedestrians aren't waiting in the drive-through lane itself, they generally still tend to be about, crossing from the restaurant to their car (often with children coming from play areas) or walking on a sidewalk in front of the restaurant. If it's not safe for a pedestrian to stand in the drive-through lane, why is it any safer for them to walk in front of it? (In one case, a police officer was struck while directing the traffic in and out of a Sonic drive-in.) The very presence of the drive-through lanes may lull drivers into thinking they are in a car-only space, with only their Chalupa standing between them and the street. Pedestrian safety is indeed one reason many communities don't want any drive-throughs in town and have sought to keep them away. Anti-discriminatory legislation may provide another tack: Would you like fries with that social justice?
Ultimately, the question of whether bicycles or pedestrians should be allowed at drive-throughs may be less important than the question of whether, in any but the most vehicularized places, drive-throughs should exist at all.
Correction, Dec. 14, 2009: This piece originally misspelled Bill Haley's last name. (Return to the corrected sentence.)