Although that said, the BBs at indoor sites just get swept up, put in a bin and go into landfill, so really we should be all bio everywhere.
The whole Bio and non-bio bb's thing as got me itching to do an experiment...
Bio-bbs are marketed as breaking down quicker than non-bios in compostable environments. Being dropped in woodland, dumped in landfill or even slightly pressed into mushy ground is not really a compostable environment.
To compost things you (normally) need a balance of oxygen, moisture, heat and "food" for the bacteria and organisms that break things down. This is normally a mix of "greens" and "browns" (grass cutting, dead wood etc).
Laying out in an open field, bb's are too open to the elements for composting to take place effectively (too much oxygen, too much variation in temperature and moisture)
Landfill, there is not usually enough oxgen or "food" for bacteria and organisms to break everything down.
Yes plastic waste is something that everyone should look at reducing however they can. But in my mind, bio-bb's are incorrectly labelled as "better for the environment" compared to non-bio bbs. I suspect there is very little difference in braking down time between the two of them in real world scenarios. The mechanical moment of soil/feet/weather more than likely breaks up bb's long before they "compost".