It’s highly automated but you still need people to watch the machines. Many Lego factory videos are available.
If this lets them source much of the plastic locally, it will save on millions of boxes being shipped across the ocean. That’s a huge reduction in carbon, even if the local manufacturing costs a bit more.
Apparently they've started phasing in pieces made of bio-polyethylene made from sugarcane. But I haven't found anything about what proportion of their bricks that makes up, and presumably they'd be publicising it heavily for PR purposes if it was a large proportion so I'm guessing it's not a very large amount yet.
If this lets them source much of the plastic locally, it will save on millions of boxes being shipped across the ocean. That’s a huge reduction in carbon, even if the local manufacturing costs a bit more.