Wildwest is the Godaddy reseller plan, so that number could be the total for all of their resellers combined, so there may be several layers of support between those domains and Wildwest themselves. I'd guess the same for companies like Enom, since a ton of registrars out there are just enom resellers.
Another thing that could be different between web hosts, and registrars that offer hosting, would be if a lot of the domains are being registered for email use only. If that's the case, it would probably help pad the numbers.
Despite their numbers, I never even consider adding a hosting plan to the cart while I'm trying to buy a domain at a domain registrar. Some of the crap plans they throw in are cheap enough to get impulse buys from people that don't shop around, or just want to keep everything on one simple payment plan, but I just don't consider most of them as real web hosts.
Save up to $96 at Dreamhost with ALMOST97 promo code (I get $1).
Or save $97 with THEFULL97.