I agree with you OP. I've namechanged to do it, because I am so ashamed.
My husband used to do it. 
He was convinced that sleeping for a few hours in the car would ensure that when he drove home, he would be under the limit. 
It didn't matter how many times I told him that alcohol can still be in your system enough to make you over the limit the next day, he would not have it. He was right, I was wrong, he was not over the limit.
I told him if I knew when he was driving home, I would call the police.
One time he got stopped. After sleeping in the car until he was under the limit (according to him, who has some sort of internal blood alcohol measuring system then?
) then setting off in the early hours of the morning.
The roadside test showed him over the limit. He was taken to the police station, where the machine there showed him just under the limit.
I was so furious with him. It took the police arresting him and proving that a few hours asleep in the car does not clear alcohol from your system to stop him doing it ever again.
He hasn't done it again. I have said that if he ever does, when he arrives home I will phone the police and they can come and breathalyse him in the house. I mean it.