My wife works at one of the largest law firms in the world, and trainees there makes about $10-$15/hour. On paper their salary is high, but the hourly rate is pushed far down because of ridiculously long hours. Their secretaries make as much or more than them.
Newly qualified lawyers there make $20/hour if they're lucky. This is in the UK, specifically in a London "magic circle" firm - one of the highest paying law firms in the UK. US firms in London pay up to about 1/3 more total yearly salary, commensurate with the same firms salary levels in the US, but also tends to expect even longer hours.
It's first quite a few years post qualification that their salaries get high enough that their hourly rates starts to become decent.
Average salary for a solicitor in the UK was around $37k/year a couple of years back, for longer than average hours, at a time when the national average salary in the uk was ca. $40k/year...
I'm sure there are lawyers who start out at high hourly rates from day one, but I'd be surprised if more than a tiny fraction starts out around the $100/hour rate.
Actual billed out rate from a major law firm, sure - my wife is billed out at around $300/hour as a trainee.
Good point, I was looking at it from the perspective of a client wondering "how much will I pay." As you say the lawyer doing the work won't be taking home nearly that much. I didn't know it would go as low as $20/hour though. My conservative estimate for a new lawyer in the US would be $80K/2400 hours = ~ $34/hr. How do the expected hours compare in the UK?