- egg breaks: you know you the answer is in [1,N], and will have to start stepping by one floor until the second egg breaks
- egg does not break: you know the answer is in [N+1, max], and you still have an extra egg to play with.
There is an asymmetry here. Because of it, assuming that you can improve upon binary search, N should be less than at half the maximum height. That gives you less information, but decreases the chance that you get into the 'only one egg in hand' endgame.
So the correct floor at which to make the first drop is clearly not floor 50. If you dropped the first egg from floor 40 you would do better - it'd take you up to 40 goes to find the right floor if it's below floor 40, and up to 31 or so goes to find the right floor if it's above (because you can reuse the first egg to check whether it's in 40-70 or 70-100). Floor 40 is in some sense a "more binary" place to drop the first egg from than floor 50.
If you keep following this line of thought, and remember that whenever you make your approach more efficient, you can recursively apply that more efficient approach to "what do I do if the first egg doesn't break", you'll arrive at the solution given in the article.