Hi nomadicsoul, I think I can help. The dollar sign "$" is very misleading, this number has nothing to do with the U.S. Dollar. The $46.48 in your top example means $46.48 in Steem Token Units, or STU. As you know, in the classic 50/50 post, the author's gets a 75% cut of the rewards, which is paid half in Steem, and half in SBD. HOWEVER, one STU = one SBD always, no matter what the price of SBD is. Right now a SBD is worth $2.59 in U.S. Dollars. So notice in your top example, the payout is 23.24 SBD, which is exactly half of the STU payout, $46.48
You would have received 75% of the 23.24 SBD, which is 17.43 SBD. 17.43 SBD at current prices is worth $45.14 in U.S. Dollars.

Now lets focus in on other half of the reward, paid in STEEM. In this case, the other half other half of the payout, 23.24 STU, is treated as U.S. Dollars, and is converted into STEEM at the current market rate. For example, right now STEEM is worth around 2.67 USD. 23.24 STU is divided by the market cost of STEEM, and 8.7 STEEM is paid out. Your 75% cut would be 6.53 STEEM.
I hope this is clear, but if it isn't, the moral of the story is always do 50/50 posts. The only reason to do a 100% power up post would be if the price of 1 SBD went below 1 USD. This is hard to imagine, because the crypto market is down right now, and an SBD is still worth 2.5X that. Hope this is helpful! Here is a link for more info. http://steem.supply/rewards