Value Judgements vs. Flow Analysis
Considering a self-organized team where no individual work is ever reported, how do you spot the lazy team member?
This is the wrong way to ask the question, but it's understandable since people are social animals. The question is being asked through a social filter that imputes motives rather than analyzing the process flow and identifying bottlenecks, process gaps, or impediments.
A better way to look at this issue is to look at the overall process flow. If the value chain is intact, and the cycle time of the process is acceptable, the question of whether a team member is a super-star or a super-dud is actually irrelevant. The only question that matters is whether that person adds value to the chain or whether the process routes around that person (e.g. the person is a bottleneck/impediment that could be considered "waste" from a Kanban perspective).
Let's assume for the moment that the person is lazy, but nevertheless adds value to the process. Perhaps this person is the only one who knows how to embiggen the whatsit before it ships off to the customer. While it may be tempting to replace this person with someone who's excited to show up every day and embiggen everything faster, the Law of Unintended Consequences suggests that this may not actually improve your process or cycle times. Perhaps the process can't move any faster than it does, or perhaps this person provides untracked value to the process chain that isn't captured by any particular swim lane or story card.
If you want to go around firing people for "moral turpitude" or some other social equivalent, fine. But please don't make the mistake of thinking that this is a process issue, because that's not supported by the data that you've presented.
Don't Optimize Sub-Tasks
In Kanban (as in other agile methodologies), tracking individual performance is always the wrong metric. Bob Lewis has repeatedly said:
You can’t optimize the whole by optimizing the parts, whether you’re designing a car, a software system, or an IT organization.
It's a pervasive theme for Mr. Lewis, and while the context of the referenced blog entry is slightly different than your issue, the core message is still on target. If you feel that some part of the process is not optimal, you must carefully consider whether optimizing some sub-task or role would actually improve or degrade your overall process.
If you feel someone is "lazy," you're implicitly addressing a potential optimization. You need to carefully consider your metric (Why do you think this person is lazy?) and determine whether or not it really matters to the overall process. If you are measuring the wrong thing, or optimizing for something other than value chaining, waste reduction, or process throughput, then you're just engaging in social engineering.