The key here is tested daily. The last time I wanted some sample data api it took me way too long to find one because all the ones that were recommended to me were deprecated. It's really tough to keep a free api up, because there's no incentives. You can't sell ads on it.
Maybe you could! Perhaps a sample data API that creates users like "John Chocolate Oreos," address "100 Pack Street", age 19.99, email "visit<at>oreo.com"
I don’t think Oreo would want to commit ad spend to that—it would perform worse than the display network, and worse than the Outbrain/Taboolas of the world.
