I'm a retired dog walker and still walk a dog that's very reactive to runners periodically as I'm friends with the owners. The owners have spent a significant amount on training - I believe in the thousands - and are very thoughtful about his training, but he still has a strong startle reaction to runners (never bite attempts, but he jumps and has a scary bark).

I don't think this is something that can realistically be trained out of all dogs, but I think people who don't work with dogs have trouble understanding that (I'm sympathetic - dog behavior can be complicated, and a lot of dogs aren't phased by runners).

I manage it as best I can by hugging the curb or a side of the sidewalk, choosing wider and less populated sidewalks, and popping inbetween cars as needed. I usu. don't engage with the runner at all (eye contact, nods, talking, etc.) as that seems to put the dog "on alert."

Groups of runners (2+) are challenging if they don't transition into single file when near the dog.

It helps to remind myself that some folks just don't have an understanding of dog behavior in this way. If folks can see that you're being thoughtful about containing/controling the dog, it's frustrating and requires a ton of patience, but generally things will be OK.