There are real/cask ale festivals all over, but real ale on tap is rare otherwise. A couple locals will do a cask occasionally, but the styles that lend themselves to flat, warm and oxidized aren't all that popular in the PNW. My favorite hangout has a beer engine, but they got tired of throwing out 80% of each cask.
There are a lot of issue, the least of which is there isn't the kind of infrastructure to support it like there is in the UK.
Beer has got be delivered fresh, which means you need a brewery close by that can keep up with nearly daily deliveries. A brewpub or microbrewery outlet can do that, but the beer industry and distribution industry in the US simply can’t, its set up to keep the breweries as far from the actual drinking as possible so the middle men are all happy.
The beer has to be consumed quickly. While a keg or two of some specialty beer can sit in a conventional CO2 system for some time, until enough beerheads order it and drain it, a live cask has a couple of days before it’s off, meaning there is a lot of waste. And then you have to have the very non-standard equipment and you have to handle it differently. In many cases, it’s done simply for the love of the beer, with little profit associated with it.
Then, the public does not really know what it is, or ever even really heard of it. It probably sounds like it would be some kind of “health food” beer to most. And I think the “warm flat beer” factor also comes into play, even among people who like good beer.
BTW My first stop in London, after the hotel, and a fortifying pint, was to find a bookstore and pick up the latest CAMRA guide.
Titletown Brewing in Green Bay, WI keeps one beer on cask all the time. Yesterday it was their oatmeal stout; time before it was their Bitter Cold Best Bitter. The above link does include Titletown.
The bartender was kind enough to let me try the Bitter Cold on cask next to the draft, and cask won hands down. Yes, it was warmer and flatter but sweeter, smoother, and more mellow. They're apparently trying to clear it out as it was the beer of the week ($2.50 pints all day, every day) but I was busy with their Belgian/French beers. The Biere de Garde is *fine*.