Humans ship with all the priors evolution has managed to cram into them. LLMs have to rediscover all of it from scratch just by looking at an awful lot of data.
Sure, but LLMs are trying to build the algorithms of the human mind backwards, converge on similar functionality based on just some of the inputs and outputs. This isn't an efficient or a lossless process.
The fact that they can pull it off to this extent was a very surprising finding.