Good point, but maybe a little incomplete. Can you read a contract and tell whether the courts will accept it? No, you need a lawyer for that. Can you look at a bridge or dam and tell how long it will last and under what loads? No, you need an engineer for that. You can, of course, wait for a court to rule on a challenge to a contract and judge how well it was written that way, but by then it's too late, and you've wasted money. Programming can be like that too. You judge a program by throwing it in front of users and accepting the financial (or, worse, human) consequences, but usually it's more economical to hire someone who knows what they're doing.