There are a few different ways to think about the differences between judges, and about the related problem of forum shopping:
On one model, all judges are exactly the same. They all apply the law, which has uniquely right answers. It never matters who your judge is, because they will all apply the law, and all reach the right answer.
On a second model, there are two kinds of judges: fair, and unfair. Fair judges are basically the same. They all apply the law, which has uniquely right answers. But there are also unfair judges, who don’t apply the law. So it matters whether you get a fair judge or an unfair judge.
On a third model, all judges are political. Judges are different to the extent that their politics are different. It matters who your judge is, because judges have different politics, and judges will apply their politics. Some people think this model is fair, and some think it is unfair.
On a fourth model, all judges are fair, and non-political, and apply the law, but they are also not exactly the same. The law is complicated enough that even two fair judges, both applying the law, might not always reach the same answer in every case. Neither judge is unfair, but the judges are different.
These models affect how we think about things like forum shopping and judge shopping. On the first model, of course, forum shopping is pointless, and people who complaint about it are delusional. On the second model, forum shopping is presumably bad to the extent that people with bad cases are picking unfair judges, and we should take the cases away from the unfair judges, or get rid of them entirely if we can. Etc.
But suppose we believe in something like the fourth model. Excessive forum shopping will systematically bias adjudication in favor of the plaintiffs, even though the judges are not biased. So it would be a mistake, a category error, to ask those opposed to forum shopping whether they think the judge is biased. Instead we should ask whether judges are different, and if so, whether we care if the plaintiff gets to pick the same one of the different judges over and over again. Maybe we do, maybe we don’t, but that’s the question. This is why I don’t share Josh’s reaction to the litigation over the federal district judges in Texas.