I see the video is from NZ, and we do see a lot of laser screeds here, so I'll try and explain why they're so common.
NZ is a bit of an earthquake prone country, so we build with that in mind. Instead of traditional foundations, we normally use raft slabs where possible. That starts with a flat sand or pumice base, with polystyrene "ribraft" pods sitting on top of that, then reinforcing and concrete slab. What you see in the video is a typical residential building platform in NZ, there will be no excavations into that for footings.