I don't think it's that the lawyers are undifferentiated; some are better than others, in the same way some real estate agents are better than others (source: people complaining bitterly about theirs).

The problem is that there's currently no effective way to comparison shop. Needing a real estate agent or lawyer is a rare event for most people, so they don't have grounds to make a comparison. And you can't really tell how good they are until you've hired them.

Compare to, say, an auto mechanic. In the US, 90+% of households own a car, and after a few years of car ownership, unless you're a much luckier person than I am, you've probably been to a few mechanics and had some good and bad experiences. On top of that, most of your friends have done the same, so it's much easier to get enough data to figure out who to take your car to next. And, of course, the stakes are a bit lower: a lot would have to go wrong for you to end up in jail because you picked a bad mechanic, and cars are usually cheaper than houses.

I am a personal injury lawyer, and am therefore biased. But I submit that they are decidedly not undifferentiated - the problem is that there is no real way for you to differentiate them.

If I were seriously injured, there are about 10 personal injury lawyers in my small state that I would consider. There are no obvious external signals such as billboards, websites, or marketing that convey their superior strategic skill and they just have it qualities before a jury. But if you know them, you know.

If you need a lawyer, call another lawyer (preferably someone involved in the special interest bar association for that field) and ask them who you should call.

undifferentiated to the laymen perhaps, just as I'm sure programmers are to the uninitiated. Guessing if you dug into their past cases, their degrees, grades, etc, you would see differentiation. If you were facing life in prison or the death penalty, you would probably want to know the specifics and not just "lawyers are interchangeable, give me a script to read in court -- its something we should have automated already."

Perhaps a more apt approach would be to expose more information about lawyers to the public, so they can make a better decision. There are sites that do this (showing average win rates, average payout, response time, years in practice etc).

But maybe people don't know about these sites, or there are other reasons people select based on advertising rather than cold logical analysis.