turns out it was a 6 putt for 9, not 10 (misreported initially)
this only happens at the majors, where they use antiquated, outdated scoring systems (people write the score down and hand it to someone at the end of the hole and then it gets run to the main centre and entered. It goes through a few people’s hands and if there’s an error on the score or the or an error in transposing the score at one of those check points, it doesn’t get caught.
the pga tour uses an electronic instant leaderboard system run by a rules savvy scorer who walk with each group, and their data is instantly reconciled against laser operators who use geo survey equipment on each shot to pinpoint where each shot ends up. Problems are instantly caught by the PGA TOUR shotlink truck, and corrected.
Not a lot of people realise that the majors are NOT pga tour events. They are co-sanctioned and ‘official’ for money etc but they are not PGA TOUR events.
Masters - Augusta National Golf Club owns it and runs it
US Open - USGA owns it and runs it
Open Championship - Royal & Ancient owns it and runs it
PGA Championship - PGA of America (no relation to PGA TOUR) owns it and runs it