$600/hr is the equivalent of about $1.2M/year salary. That's exceptionally rare. Unless you're being cheeky with "should be", I think you have beliefs that are misaligned with reality.
Most contractors I know don’t work 40hrs day, every week. Also if you look around at advice you’ll find that you shouldn’t quote an hourly rate, you should quote “for the job”. If you’re good and the work you’re doing is even mildly specialized you can get a job done quickly enough that the effective hourly rate is pretty absurd.
What counts as "independent expert in specialized field"? Because as an independent backend contractor (java/spring/scala/akka) that straddles the line between architectural consulting and staff augmentation (usually long-term contracts), I see real resistance to going above $200/hr since even in the bay area you can hire full teams from vendors at around that price point for man hours.
Seems below average for law firm partners [1], and there's a lot of them out there, so it doesn't surprise me at all that technical consultants with genuinely rare skills could command hourly rates like that.
