Lawyers, like most well-paid professionals, have strong incentives to act ethically. They generally have more business than they can handle, so they don't need to rip you off, and getting caught doing so (which would happen the minute you spoke to another one) would have seriously negative consequences, up to getting disbarred.
Of course just like doctors, it cannot hurt to get second opinion, because lawyers are of course not all ethical or infallible.
So how does it relate to IT consultants - would you say that it is completely different with lawyers? Maybe all IT consultants are ethical, too, but many are still clueless. Still, they manage to find their customers, and they are in high demand, too. Are lawyers in general less clueless?
I must admit that it often freaks me out to consider that other professions are just as messed up as the software world. For example, in medicine there is in all likelihood an equivalent to LISP and an equivalent to Java. Many hospitals might have invested in useless expensive machinery (Bea Weblogic, Oracle...), and now use it on their patients, even though better treatments are already available.
If not, I wonder how medicine has solved the problem that the IT world can't seem to get a grip on.
I don't see what IT consultants have to do with lawyers, or how you think the two relate. Just because people waste money on IT consultants does not mean hiring a lawyer is a waste.
Also, anyone can just call themselves an IT consultant. You have to go through schooling and pass a test to become a lawyer. The barrier to entry is a lot higher.
Of course just like doctors, it cannot hurt to get second opinion, because lawyers are of course not all ethical or infallible.