The problem is in the very short term. For example, the 1000 year old lava flows in Arizona.
Indeed, this 1000 years is essentially 0 years for dating something with a 50 billion year half life. I would hardly expect them to tell them apart, since 1000 years is such a tiny fraction of 50 billion. However, I might have expected that perhaps 1.3 billion could be distinguished from 0, since it is 2.6% of the half-life...is it your thinking that it should be or that 1.3 billion is still too young?