In my neighborhood there is 30 inch, 15 inch, drilled at 7 inch or so, and twin row planted on 30 inch centers (Great Plains or other that plants 2 rows 7 inches apart, centered on a 30 inch spacing).
Everybody makes a good case of what they do works well.
Drilled 7 inch rows shade out weeds early, but can get white mold more easily.
30 inch corn planter uses far less seed reducing cost, as its more accurate at planting, but will allow more weeds to sprout before rows close up. In the rare times you get bad crusting of the ground right after planting, the seeds closer together in wider rows can push through the hard ground easier - more close neighbors to help push.
The twin row or 15 inch are often a good best of both worlds situation.
Depending on the year, have seen top yields on all of the different setups, they all make good bean populations.
As I have low wet ground, don't care for the disease problems drilled beans can give, as well as the extra seed you use.
I've done 15 inch rows for years, and like them.
This year used the corn planter at 30 inches, just how it worked out. I'm sure I will be happy with them.
Likely go back to the 15 inch next year.
It's all workable, depends on the weather each year which setup worked best that year, will be different next year.....