A lot of that has to do with what technology is there. If the nearby DSLAM is of the G.DMT variety, it will top out at about 8/1, and was very common a decade ago. ADSL2, 2+, or VDSL have more capacity. Also keep in mind that just because a CO is close does not mean the cables go straight towards you. Every now and then, the cabling takes a circuitous route, and the wire length (EWL) is much longer than the straight run would be.