I don't disagree with what you're saying but I want to point out that it's rather unusual for (American) ambulances to carry blood, and probably more of them should.

https://www.redcross.org/about-us/news-and-events/news/10-wa...

Correct. The only ambulances that typically will stock blood are specialized NICU ambulances and HEMS (helicopter). Although more progressive agencies are looking more and more at part blood products.