Fastbrick Robotics robot building a home - GIF

[BuffaloJohn]

So it would be faster to just stack these up by hand, as I don't see any mortar in those joints.

There is an adhesive on the underside of the block before it is placed. You can't see the underside, but you can see evidence of the adhesive on the lower courses - looking at the start of the video and also at the 1:30 mark.