Maybe the perfect roadmap says the trash picker needs $600B investment and will cost $4M per unit in 10 years time, if we solve all the problems.

That trash picker may never compete with a human. There's no reason to assume it will.

edit:

> none of those things strike me as any more challenging than the control software

Maybe the difficulties of motors and batteries are not intuitive. Look at their improvement rates over time. It's a far cry from transistor counts or FLOPS. And look at the performance and efficiency of humans and other animals. We are absurdly strong, light, efficient and cheap to maintain. The gap is huge and not closing quickly.