Yeah! I think of that 'intrinsic difficulty' in sort of information theory terms. In that, given the context of where we are and where we want to be, what is the minimum amount of work needed to get there. If that minimum work is a large amount, the problem is 'hard'. This also accounts for the change in difficulty over time as our 'where we are' gets better.

Line work is certainly still hard from a toil standpoint. But academically, little of that total effort is intrinsically necessary, so the work is in some sense highly inefficient. There may still be aspects that need human intervention of course, but the less that is the more robotic the task.

In theory, anything that's already figured out is a candidate to be offloaded to the robots, and in some sense isn't necessarily a good use of human time. (There may be other socioeconomic reasons to value humans doing these tasks, but, it's not absolutely required that a human do it over a machine)