Building pyramids out of single stones is still very labor intensive. So modern technology might save a lot of workers in transporting the stone, but they still have to be placed individually. To see what modern technology can achieve, look at modern construction sites, like skyscrapers or especially the work done at the spillway of the Oroville dam after it broke. Large parts of the spillway had to be replaced in a couple of months, laying enough concrete to build a pyramid - I have to look up the exact numbers to see how large exactly. Additionally a huge amound of debris was removed from the waterway. All this by a few hundred workers working in 3 shifts. Check out the construction videos here: https://www.youtube.com/user/calwater/videos