I added three drive-throughs as separate ways a while ago, then recently removed them (#178594082) after I read that only roads separated by a physical barrier should be mapped separately.
It made sense to me that I would map them separately, but I want to be sure I’m following applicable conventions. Is there anything I should know about how to approach this?
Here’s a screenshot of where I had previously mapped each drive-through:
Good question! I treat this as an exception to the physical separation principle. Sure, nothing is physically preventing a driver from leaving the line or cutting in line, but then the little one in the back won’t get their Happy Meal. 
The pedantic solution would be something like driving_side=left for case 1 or service:lanes=drive-through| for cases 2 and 3, but it would result in some very unintuitive geometry in case 2. These are the easy cases. There are plenty of other common cases for which a single way simply can’t describe the geometry.
On a through street, the main benefit of the physical separation principle is that a data consumer wouldn’t have to do gymnastics to reconstruct lane guidance. But even though the drive-through is separated by a mere lane divider, I don’t think people normally think of it as a lane.
… which would be much better for their health … 
I agree with Minh. How is this situation, principally, different from service=parking_aisle, where the parking spots are only indicated by paint?
As with most other things, I regard the principle of physical separation as a good-practice guideline, but not as a commandment. Yes, using a single way for situations where its multiple lanes are not physically separated indicates that an emergency vehicle, or any vehicle in trouble, may cross to the opposite side in case of emergency. But a map we are creating is by definition a model of the world with all of its limitations, and as mappers we have to find a balance between usability, accuracy, and complexity of that model.
In examples 1 and 3, I’d not map them seperately. For 2, only the cutoff where the inside drive-through lane becomes separated to go behind the outside lane’s menu would be something I’d map.
By the way, it just occurred to me that case 1 has drivers going eastbound so that the driver’s side rolls up to the drive-through window. If mapped as a single way, it would be a rare example of needing to indicate that the rule of the road is reversed from the national norm. Just a taste of the many weird things that happen when we combine these different purposes of the roadway. (On the other hand, it would be kind of neat to be able to query for these cases.)
I’d consider it more of a case for oneway:lanes rather than driving_side=left. The latter would indicate that the other way was oneway too, but that’s not the case from what I can see.
Only two cars can fit side by side on that access road. The other side appears to be westbound only, based on the angle of the adjacent parking spaces. Not the best signposted example, to be sure.
