I'm curious why you claim that, although I probably shouldn't expect much as your message boils down to an ad-hominem without even telling what you object to. Sieverts are weighted by biological effectiveness of the particles, so that when comparing committed doses from different sources ("nature of the exposure") they are intended to be comparable. Whether scientists have been successful in making them comparable is a topic that's perhaps more suited elsewhere than web-site discussion trying to find comparison points for dose rate, but that's certainly the intended purpose of Sieverts.
The wording on the "10mSv/yr average, 20mSv/yr max" claim makes it sound like it is committed dose. As I pointed earlier I'm aware geiger-counters don't measure Sieverts, at most they will show air gamma-ray dose at midpoint of body if calibrated correctly. In general this would be in ballpark of the minimum committed dose. If they ingest, inhale or touch anything, it'll be higher of course. In a car or cleaned up house it'll likely be lower due to distance and shielding. I've brought up the geiger-counter readings only as a means to show the average dose can't possibly be as low as 10mSv/yr, and the maximum certainly isn't 20mSv/yr.
However the Wikipedia quote on smoking is misleading if not outright incorrect, as I checked the original sources. The wording indicates it's whole body (effective) dose, but checking out the original source turns out it's only bronchial epithelial dose, so that is not really comparable to the others.