Also - note that not all licensed attorneys are practicing, so it may even be more like 1 lawyer-day/year per worker.
Something like LegalZoom seems like a reasonable option for 80+% of all deals that currently use a Lawyer.
Edit: As to policy changes, a trade association could reasonably cover all most / all cab companies or even Hospitals.
It's basically the same as the choice between using stock Wordpress or hiring a developer to customize it for you (or to make you a custom CMS), except that the consequences are usually more dire.
Also, some of your examples are a bit odd. I don't know anyone who's hired a lawyer to buy a house or hire a housekeeper/nanny/gardener--is that some sort of weird Silicon Valley practice?
A lawyer's job when buying a house is mostly dealing with the mortgage. They can explain the mortgage paperwork to you, and find traps like balloon payments or weird escrow structures that a layman might miss. If you pay out of pocket, there's generally a lot less for a lawyer to do.
There are of course exceptions where a lawyer is very important, like reviewing the bylaws of a condominium or homeowners' association, or explaining unusual clauses in the sale contract. Unfortunately it's hard to tell when you've run into one of these without having past experience or hiring a lawyer.
IMO, a large part of that difference is from how involved the State government is when selling a car. Property can also have far more limitations like a local homeowners association or right of way easement. Still, taxes can also be vary complex but few people need a Lawyer to look at them.
Simply covering the 80% case can add a lot of economic efficiency.
Lawyers time by the above calculation = actual hours spent working by lawyers
$350 = rate for BILLABLE hours by the higher end of attorneys
Lawyers don't bill 8 hours for 8 hours spent working. There is a lot of overhead.