What Andrew said, to a great degree. The PLB market is relatively small, promotion of any sort is fragmented by the multiple players, none of which are very large, nor have they proven all that capable or fast on their feet. COSPAS-SARSAT secretariat isn't a player in promotion, it's just an international agency that oversees the various national partners. The U.S. or Canadian govt. hasn't the promotional means, flexibility or anything to compete against private industry in this regard. Many there don't even see it as a problem, for a variety of reasons.

Then add in the value added capabilities of SPOT vs a PLB. PLBs are limited in this regard as a result of the standards to which they are built. Nothing stops a PLB manufacturer from adding in capability, but it has to be in addition to the basic PLB capability and at that point cost and size/weight kill it. If there are changes in the standards, perhaps they will have a better chance in this regard, and that is under discussion. However, they represent fairly radical changes to accepted practices and that's hard to make happen. Will it come at all or come soon enough? Who knows?