I have inspected thousands of quick service restaurants and convenience stores in the last decade. Every one of them have counters that match the ones in this discussion: counters with napkins, condiments, straws, cups, cup holders, etc., counters with coffee dispensers, ice cream, prepared food, etc. They are a type of service counter because they fall under Section 904, although the section does not require that they comply with the counter height requirements for service counters; they indeed function as a work surface (as some have noted) because customers must often place items on a food service counter and perform some activity (mustard on a hotdog; cream in a coffee etc.), but they do not appear to be considered a work surface by the Access Board or the Standards (and if they were, they would require front approach and knee clearance, which would be untenable in most food service lines).
While the previous version of ADAAG included a blanket requirement specifically for counters, the new standards do not. There are requirements for specific types of counters (Sales & Service Counters) and surfaces that may include counters (Dining and Work Surfaces), but not for counters in general. The question here is: "What do the Standards require for counters in food service lines?"
In a typical food service line there are a number of elements: display cases, tray slides, self-service shelves and dispensing devices, and counters. Counters are actually referred to in the Standards at 904.5: "Food Service Lines. Counters in food service lines shall comply with 904.5."
Only problem is, no specific requirements are delineated in the referenced sections for the counters themselves, except by implication. 904.5.1 states that self-service shelves and dispensing devices must be located within accessible reach ranges, which usually implies accessible side reach, and 904.5.2 regards the height of tray slides. When side reach is over a counter, that counter becomes an obstruction and must comply with the limitation for reach ranges over an obstruction.
I believe this is by design. If there are fixed or built-in elements on the counters (including dispensing devices attached to 220 outlets, water, or gas), they must comply with reach range requirements over an obstruction (the counter) which limits the height of the counter to 34 inches AFF. The obstruction does not have a depth threshold so any distance over which one must reach (even 1/8") might be considered an obstruction, making it virtually impossible for the counter to not be an obstruction.
If the counters or the elements on the counters are not fixed or built-in, they are not subject to the design and construction Standards, but they are still subject to the ADA's equal access and nondiscrimination provisions, which gives opportunity for a lawsuit or enforcement action by the feds should an element not be readily accessible and usable to a person in a wheelchair. Whether the ADA Standards determine this for freestanding objects is debatable as there have been no cases that I know of adjudicating the issue, however I counsel my clients to use the design Standards as a guide whenever practical to be safe.
Finally, while Safe Harbor may allow existing elements to be 54" AFF for side approach, the obstruction height is the same - 34".
Ken
