That data is not being universally collected in the same way is most definitely a problem. It adds to the uncertainty.

But the bigger problem is that it can take up to a month for this virus to run its course in an infected person. Some recover quicker, like a week to 10 or 11 days, but some it takes 4 weeks. So people that become infected say today or yesterday (like Rand Paul) are counted in the cases, but their outcome is probably weeks away. The only people that have currently died in the US are people that were infected several weeks ago. That is why you cant use the current cases that have not been resolved (are just beginning and the patient probably isn't even sick yet) to figure the death rate. Its preposterous.