This used to be the standard practice where I worked doing client web development. Random Fortune 500 Company is not going to buy into an iterative development

This used to be the standard practice where I worked doing client web development. Random Fortune 500 Company is not going to buy into an iterative development process, because the person at the client company is usually some peon with little real power to adjust budget or requirements as necessary. That is, until it's too late, and their superiors are breathing down their necks because the website doesn't do what they didn't say it should do. Plus, if you don't use an iterative process, you can bill your client for massive change orders. So there's no real incentive on either side to change the process, unless both companies "get it" from the start that you can't make quality software this way. The likelihood of this decreases dramatically the larger the client.