It's not like people get out of college uniquely qualified for writing a Twitter clone. The same people that use machine learning for ads could also use it for sorting trash. And manipulating it would be a hard problem for robotics.
As Larry Ellison and other godfathers of the start of the IT industry once said (paraphrasing), "It's impossible to find someone who has the necessary skills and 10 years in the industry. Just hire the smartest people we can find and let them figure it out." Worked before, why wouldn't it work again?
Larry Ellison had two big advantages, though - a well-circumscribed problem domain and an obvious business model. Recycling has neither. It's a much more difficult problem.
Receive waste. Process it. Sell the recycled materials, get rid of the byproduct.