That's true. I agree with Wizard here. Besides Jasmin, a lot of girls (Ginza and non-Ginza) offer anal, but not to all bros.
I don't think it's something the WL's are comfortable with unless they feel they can take you physically (size) and/or mentally (attitude/personality).
Basically, just because an AR says a WL offers a particular service, I don't think you can automatically assume its on offer 100% of the time. YMMV obviously.