What you do see in law that you don't in engineering is the up-or-out pressure in big firms. You either make partner in years 7-10 or you go find another job. But if you do make partner (possibly at a much smaller firm than where you started), you basically get to do technical work for as long as you want. Partners do some business development and management work, sure, but they're still the ones that go into court and argue the motions. And in that role you only get more valuable with age. People go to lawyers when something has gone sideways, and all else being equal they want the cool-headed guy with 20 years of experience over the young hot-shot.