Also, you can just use a fake name, address and email when signing up so if they verify you as a first-time user on that you can easily bypass and have free trial forever. They can better use the CC details for this verification. And it's trivial to reject those single-use virtual CCs if they want to. It does actually serve a functional purpose in this case to request CC info.
Of course they definitely still hope you forget too so they can charge you.