@jfmezei most geolocation is based on Class-Cs, and we're not big enough to warrant that for our PPPoE customers... yet.
Also Google et al. may use varying indicators for the location signals; maybe a single Android user on WiFi could shift the entire notion... or whatever. Somethings may go off Whois too, or something normalized from one of those addresses....
IP-based geoloc isn't exactly an exact, nor accurate science.