Clearly you've never worked with contract developers whose only purpose is to write a crap ton of code to get a "feature" out that crashes as soon as it encounters the real world. As they say, "doveryay, no proveryay" and it's served me well.
I'm sorry if this might be common knowledge, but I've honestly never heard this and can't understand it.
Is it saying that it's better to do something than to (formally) prove it, like the opposite of (I think) Knuth's famous quote?