Has anyone had any experince that suggests that blood type is useful ID data?

Military ID's apparently include blood type, and some civilians talk about it, too. IME, no er docs will order blood based on history. Must be different in the military. Most er's have access to low titer O negative blood, low risk stuff to transfuse really quickly-but a cross-matched unit is available in about thirty minutes from most blood banks. Cross-matching-actually mixing a bit of the recipients blood with the donor unit to see if they react, indicating incompatibility- is done because blood types are not as simple as A-B-AB-O and Rh- there are dozens of antigens that affect compatibility.

So why is blood type on ID tags?