That is true but not because of the "lawyer monopoly" because of the bar requirement. Google has their own legal department and if required they could easily find a 50$/hour attorney to file everything they write in court...
In my opinion the real reason is that some areas of law like patent litigation require highly specialiced knowledge that is almost impossible to acquire outside of a few special firms. An unexperienced law school graduate trying to do patent litigation would be like a med school graduate trying to do brain surgery - it just isn't feasible without years of additional training by someone who is already an expert in the field. But while after medical school this is provided by the residency programs at hospitals, all that exists for lawyers is starting as an associate at specialized for-profit biglaw firms - who have no interest in "teaching" as many people as possible, but raher in maximizing their billing rates...
I would argue that hiring lawyers is like hiring developers in SV. There are many developers but if you want to hire A class developers, you have to pay A class rates and compete with everyone else trying to hire A class developers.
Lawyers are no different. If you want to hire A class lawyers, you're going to pay A class rates.
The "A class rates" for developers rarely approach the minimum rates for legal services. The highest rate I've received from a consultancy was $200/hr, and they were working in an extremely specialized area with literally the best developers money could buy -- the only fundamental builders of that technology that weren't on board at that company were those who refuse to take a job. I know that Percona lists $300/hr as their rate, and we have the same story here; extremely specialized field, developers that are and have been deeply involved in the development of the technology for most of its lifetime. Generalized high-powered development help typically maxes out in the $100-$150/hr range, at least in my experience, and even that is difficult to get outside of California.
$250+/hr is the common baseline rate in my area for real commercial legal services (that is, more than emailing a template for a contract), not the "A class rate", and I would guess areas with higher cost of living are worse off. I have associates that pay $450-$500+/hr for their legal help. I know of lawyers that charge $750+/hr; that, you may say, is the "A class" rate for lawyership. Note the disparity between development consultancies and legal firms -- we max out near a law firm's minimum rate.
Comparison to other highly-skilled professionals, like developers, is indeed valuable, but only further demonstrates the exorbitance of legal pricing.
This isn't relevant at the price points we're discussing. I've never known a 16-year-old to get paid $100/hr for his consulting services -- they are usually excited to take gigs at $15/hr, and the problem sets they encounter are usually tractable for their as-yet basic skill set. I can say as an individual who has made this progression from fresh-from-high-school freelancer to full-scale consultancy owner, you really hit a ceiling once you get around $50/hr. Unprofessional developers usually have significant difficulty crossing that threshold, at least in my local market, and there are not many absolutely incompetent developers floating around at higher rates. Most of our peers that can remain in that price range are at least respectably competent, even if we're still better than them.
Another way to think about it would be how high would A class programming rates be if programmers had to be members of an official organisation and if the education for skills at the high end was only accessible to those who were already members.
In my opinion the real reason is that some areas of law like patent litigation require highly specialiced knowledge that is almost impossible to acquire outside of a few special firms. An unexperienced law school graduate trying to do patent litigation would be like a med school graduate trying to do brain surgery - it just isn't feasible without years of additional training by someone who is already an expert in the field. But while after medical school this is provided by the residency programs at hospitals, all that exists for lawyers is starting as an associate at specialized for-profit biglaw firms - who have no interest in "teaching" as many people as possible, but raher in maximizing their billing rates...