I think the main problem is that most of the expertise in mastering, cutting and pressing records, as well as the equipment, was lost in the years when vinyl more or less disappeared from the market. Records are, according to an article I read last year, now being pressed in many cases on machines which are well past their useful life-span and are being kept working with all sort of desperate repairs, and in some cases by people without that much expertise. Quality control also seems a problem - I get a lot of records which have been scratched inside the sleeves as grit has found its way in. Not a problem I remember in the 'old days'.