One thing I’ve always been curious about is why law firms so aggressively meter. Wouldn’t most arguments you’d apply to software consultants apply to them as well?
It's something they are expected to do for their clients, so within reasonable limits doing it to their clients is expected and shows a serious professional attitude.
For example a defense Attorney defending a DUI charge will likely be a flat fee. They will also charge according to what it is worth to you.
e.g. If you were Palo Alto's most successful real estate agent, and were at risk of losing your drivers license, you will be charged accordingly when you show up at the doorstep of a prominent defense Attorney.