HPs instant ink program lets you print full page prints in full color for the same price. Costco charges $2 each for 8x10 enlargements. Given that HPs base add-on rate is $0.10/pg, there are environments where that could make sense. Kinkos and Fedex routinely charge $0.50/pg for color prints.

Sure, I wouldn't print 500 pages of B&W text on instant ink, but when printing things that require color, it's not ridiculously expensive.