Yeah, I think took that into account in my estimation. Not every lawyer will be willing to work for free for a friend (it's like doctors constantly being bombarded for free medical advice, or software engineers constantly asked to provide free IT services to fix people's computers/phones/routers/network). I also assume that law is highly specialized, so a lawyer specialized in Constitutional or Patent law may not want to handle Family law, Contract law, Employment law, or Personal Injury law.
I figure the number of lawyers willing to do such small favors is in the range of 1% to 10% of the 1.3M (wild guess). So if each of them had 100 friends-and-family "clients", it still wouldn't add up to "pretty common".