True, that's a good point and I pretty much agree with you entirely. I didn't really make a distinction between argument and anecdote. Basically I think it's being glossed over that there is a blatant up-front cost to testing. Write the tests first and you guarantee that you eat this cost. An argument can then be had as to whether the upsides are worth it or not.

I would love to see data on this, but to my knowledge there is none. (And it's unclear how to even design such an experiment/study to get meaningful results.) The statement I made that it's a lot of effort to do testing before code is of course pure anecdote. But that goes both ways - so are the claims in the original article as far as I can tell.