These are intentionally different. 1 STEEM is the minimum enrollment level, but people seem to think that 1 STEEM will get lifetime upvotes on EVERY post, no matter how frequently they post.
When we started out, 1 STEEM was enough for upvotes every day, but that was before micro-taxes on every upvote and STEEM price was 24 times higher than then than it is now.
Realistically, since people interpret upvote values in $ (or STU technically) they should think of SBI enrollment cost in dollar. Nobody would realistically expect $0.012 daily from a $0.40 investment, they just don't do the math.