Inefficiency is no excuse.
I'm sure there are as many lawyers who love or hate their job as there are developers that do... some people (like myself) love doing the work but I have many colleagues who find it tedius and boring. I would say also not an excuse.
Security or data integrity flaws are no more apparent than contract holes, and often are equally as disruptive.
Developers aren't at the beck and call? Lol I would say that's a misconception. Late nights and weekends are NO stranger to developers. Especially in actual companies (vs independent) where deadlines are approaching its very common to be strongly encouraged (read: required) to work weekends.
It's more likely that the combination of cheap alternatives (outsourcing, developer living in a carboard box in san diego, etc) are numerous and you don't need indepth knowledge to click buttons on your program to see it works like you wanted it to but you do need all that knowledge to look at a contract and confirm its legitimacy.