Then they are morons, because the U.S. Draft ended in 1973, so by the "mid-1970s", there was no draft.
LOL! That it is weird, isn't it. I checked wiki's source for that info and found this: "With Nancy Wilson's addition following completion of College in 1974, the band was re-christened Heart and moved to Vancouver, British Columbia after manager Mike Fisher [actually 'Flicker', not Fisher] found out he was to be drafted by the United States Army."
http://jam.canoe.ca/Music/Pop_Encyclopedia/H/Heart.html
Also, someone, around the time of your reply, made a correction/clarification to the wiki article (I highlighted new addition in bold type). It now reads:
"By the mid-1970s the male band members were eligible to be drafted to Vietnam (The United States Left Vietnam in 1973 - Conscription ended in December 1972), so the band relocated to Vancouver, British Columbia, Canada.[3]
http://en.wikipedia.org/wiki/Heart_(band)#Success_.281975.E2.80.931982.29