Because they're still treating them in some regard(before being overwhelmed).

However once things get even more overwhelmed, you have bad cases become critical leading to more fatalities.

The going figure seems to 20% are badly impacted, with 5% of that critical. Some of that 15% will become critical without treatment that might not be available. Thus impacting people <70.

If you don't mind, Where did you find this information? I've been searching for a breakdown of all fatalities so far by age group (raw numbers, not just average percentages) and could not find it.

Thus far. Most of the younger critical patients are not out of the woods yet. Also, many of those are left to die without treatment or assessment because there aren't enough ventilators for them.