No, almost nothing of the $200 actually goes to the author. A typical share goes like this: (concrete numbers for Germany) 50% of the sticker price goes to the book seller, 7% to tax, the remainder to printing, typesetting, logistics, the publishing house etc.
A typical author would get somewhere between 4-7% of the net sales. Most books, especially advanced science books, on the market (not your College 101, not NYT bestsellers) sell only in the order of hundreds, maybe a few thousand copies. The vast majority of books doesn't even earn the advance back. The reason why they are often not good, is that it takes months to write 500 pages of well-thought out, well-delivered material, and the incentive to do that for $5000 is relatively low.
A typical author would get somewhere between 4-7% of the net sales. Most books, especially advanced science books, on the market (not your College 101, not NYT bestsellers) sell only in the order of hundreds, maybe a few thousand copies. The vast majority of books doesn't even earn the advance back. The reason why they are often not good, is that it takes months to write 500 pages of well-thought out, well-delivered material, and the incentive to do that for $5000 is relatively low.