One doesn't deserve a high valuation just because the problem they are solving is hard.

The company he came from, Amazon, has more cash than anyone could raise. They have logistical expertise and are perfecting same day shipping at a national scale.

They also offer Amazon "Fresh" which is essentially the same service except they don't skirt labor laws by classifying their employees as contractors.

And non-tech people actually trust Amazon and order quite a bit from them.

For them to succeed outside of a few big cities would require gross negligence and incompetence by Amazon, which isn't impossible. But seems unlikely.