The relationship between attorney and client is one of the most complex business relationships across all professions. The high duty that lawyers owe their clients requires them to put the clients' interest first. Yes, this means putting their clients' interest ahead of their own interest, even when it comes to payment.
I'm always amazed by the collection tactics of most law firms. The primary weapons tend to be past due notices, strongly worded letters, and -- worst of all -- leverage. Now, attorneys aren't supposed to wheel leverage against their clients, but the issue of payment complicates matters sometimes. Lawyers too often use their position of strength over their clients to get paid.