TDD only works when you're building something to a pre-defined spec. But so much of what we do has no spec, or a spec that is constantly in flux. Add on to that the fact that anything we would need that does follow a strict specification is probably already implemented, there ends up being very little need for TDD in the wild. It's great if you need it, but few people actually need it.
Still, if you start your day building one thing, I strongly assume you know what you're going to build that day. And you start with writing a test to confirm you actually built at the end of the day the thing you planned. Will you keep that test? Maybe yes, maybe not, but you got your confirmation at the end of the day. This is TDD for me.
