The main difference here is that in one scenario it is a man saying to do something ridiculous. In the other it is God saying that you should do what he frikken says because he is God. Sometimes the justification in an order is found in the authority of the person giving it.
That's kindof moved the goalposts rather a lot (from "Most Christian laws make sense because of hygeine" to "Christian laws should be followed because God says so and he's God").
I'd like you to expand on that view. Does God saying it make it ok because he must have a secret reason for not wanting people to collect sticks on Saturday? Or is the stoning justified because God simply cannot be disobeyed, with the law itself being irrelevant? Or is it because God somehow defines what's right by saying it? I'm kindof interested.
I would say that there are often justifications and sometimes not. According to Genesis, God put the fruit of good and evil in the garden of Eden, but why would he do such a thing? There is no real REASON not to eat it, he simply said they shouldn't because they shouldn't. God gives laws on some occasions to test loyalty, not logic. Think of it in the perspective of a parent. If mom says not to eat the chocolate because it is special and you eat it, whether or not she actually had a reason to keep you from eating the chocolate, it was a wrongful act because you defied her rule. Now if mom says you CAN eat the exact same chocolate, was it wrong that you ate it? No, because she didn't SAY it was wrong.