Many developers are hard to convince to use this methodology. It is very often difficult for a developer to understand completely what the code needs to do. Yet - they want to proceed to write it anyway? It's kind of a flaw in the thinking process.
Lucky that you are smart enough to know that there's a better way..
Figuring out the test for some code is always the hard part... that's why we like to do it first, and get it out of the way.
TestDrivenDeveloper.com is a John E. Boal web site. Please see also my personal blog and my Agile Development blog