To be honest I haven’t noticed this behaviour so much in our group. I’ve seen some cases on pickups that have many slots, so usually a pickup does not go missed. When thinks like this happen is usually connected to a person’s general lack of commitment or capability to be organized and communicate with others, meaning that the person will also do other things like arrive late or maybe not show up at all.
We’ve discussed all of these problems a lot and often times it gets better when the community talks to the person and demands more commitment, but usually complaints of this kind needs to go through the core team or “organizers”, who are seen as some kind of authority on dictating the rules, which is obviously far from the ideal on how a self-organized community should work. Especially when we are not doing the pickups in question so often and only hear anecdotes like “person X is often late” or “person Y did not show up”.
I believe there’s not much to do on this through Karrot, it is rather a long and patient, often tiresome, work of community organizing. However, being able to check the history of a store or a pickup is a good way of establishing patterns beyond anecdotal evidence, for example to see if a person is often signing up and dropping out. Then we know we should have a talk to the person.
I also encourage people to write the feedback if someone’s late or did not show up, but that has never been obligatory and people do not do it so much because they are afraid to point fingers, I guess. Maybe the feedback feature could be improved, if people could confirm that others who signed up actually showed up, and on time, and this is displayed in a less personal way. Also being able to have some numbers on people’s profile (how many pickups, how many last minute dropouts, how many stores pickup was done, etc) could be a way to establish more clearly the person’s reputation or performance? On the other hand we might want to avoid these quantifications? I don’t know, just thinking out loud…
Sorry for the long answer, I digressed on a very complex topic!