Just a quick note to chip in that most cases aren't about whether the defendant "did" it: they focus on whether the prosecution's evidence can *prove* it, and/or whether there was a "reason" for it being done or an interpretation of the law that would negate or diminish its illegality. It is therefore the lawyer's job a lot of the time to poke little holes in the prosecution's evidence, or to find "legitimate" reasons to excuse or mitigate or condone the behaviour - not to prove your client didn't "do" it (you don't ask your client if they're guilty, it's just silly practice). And most of the time the motivation for this isn't justice. It's to get the best possible outcome for your client. Not, and this is the bit I always had a problem with, to get the outcome your client *deserves* (morally, ethically, etc). I always want to cast judgment.
Of course I'm speaking in broad generalisations, and only from what I personally have observed.
Also, most clients aren't millionaires, but lawyers still charge what they charge. When I was working for Legal Aid we had barristers giving us deals for clients where they would do a 30min Mag's hearing for $500-1000. Rather than looking at how many big names are on trial, it might be more accurate in terms of the current debate to look at what barristers and solicitors charge - because, except for pro bono, the cost is the cost and people will just (have to) find the money somewhere.