I know very well Batman Universe series just collects Batman Giant's stories. Thing is unlike Batman Giant it organizes them into just 6 stories not 12. That's what Batman: Universe collection is based on.
Also most of all Batman Giants also collect other stories which are from past comics. Batman: Universe Vol 1 too doesn't organize them by the Giants. That's how we'll go by it. Saying it's a Batman Giant reprint is a mistake as it causes confusion as to what's being reprinted.
Even if you say it's only reprinting the Batman Universe stories from the Giant, it's redundant when we can simply list Batman: Universe issues (which btw are fewer in number so more convenience). Please don't create a storm over this, let it remain the way it is.