Sorry, should have been more clear. Did not mean ranking order per se... More so trust and standing with Google.
I help folks with G+ L problems all day and lots of the problems over past year have been re traditional service area businesses like plumbers. Hundreds of thousands of listings were deleted, many were down for months. (Largely due to hide your address violations which does not apply here but there are a myriad of other problems tied to SABs - which in Google's eyes often tend to be on the spammy side.)
Also Google is now deleting SABs from Map Maker so you can't see history to do troubleshooting.
Additionally SABs are not supported for merging with G+.
Specifically with attys, many set up additional offices - often times virtual offices that are not staffed - which is a violation. Sometimes to try to avoid getting deleted, they'll set up service areas for these additional locations. If you work with Google a lot you know she often paints with a broad brush and deletes or suspends listings that follow certain spam patterns. Throws baby out with bath water so to speak.
So in my opinion there is just sort of a bias I guess you could say against SABs on multiple levels. That's gradually changing.
I try to teach folks to learn to think like Google and avoid possible spam filters or things that could trip a red flag. I just feel like why create unneeded attention, possible closer scrutiny or risk the algo making a wrong assumption, over a setting that does not have any upside at all. Google looks at data in aggregate. Almost all attys serve clients at their office and do not have service area set up. So why be different and risk it. Especially if no benefit.
But again I help people recover from problems all day long, after they've done something that's already tripped them up. Therefore I see more problems than most and tend to be over-cautious because I know how time consuming and tricky it can be to fix something on Google local AFTER you get suspended, deleted or a rank penalty.
Hope that helps clarify. Was in a rush before and maybe should have explained better, but it's alot to explain and even in this reply that's only part of it, but I think enough to help highlight some points.