Logistically, it's not going to be any harder for Sanders to get many of his policy goals passed than it will be for Clinton, unless her policy goals are scaling back Social Security/Medicare and handing out corporate tax breaks, of course...and even then, they'll probably just obstruct because it's reflexive for them at this point.
Why is nobody calling Clinton's ideas pie in the sky? Do people think the Congress is just going to get along with her splendidly and say "anything you want, ma'am"?
I think people are saying Sanders's policies wouldn't work even if they were passed into law.
And require a hell of lot more cooperation than just Congress.
I don't think we should pretend that most of the complaints about this are that nuanced. Besides, a lot of what Clinton is purportedly proposing is 80% of the way there compared to Sanders with respect to cost, complexity and logistical hurdles.