$1810 includes taxes and fees. $1643 is the base fare, so no taxes and fees. I said that Google Flights isn't displaying the cheapest options and to use Momondo or ITA Matrix, but provided the Google Flights link for consistency with what people usually provide.

If you look at the Lufthansa screenshots and do currency conversion or look at the ITA Matrix screenshots or Momondo screenshots you'll see a price in a similar range to the one in the thread title.