Bettman thinks all the info like salaries etc. are to be guarded like nuclear launch codes. Until the NHL lets the public have this kind of info and more importantly injury info, the majority of North America will never take the league seriously.
But, more than salaries, IMO the NHL doesn't want the public to know that the teams that drive the NHL gate revenue the most ( the Canadian teams ) are the teams that make up most of the no-trade and no-move clauses.
I think if the NHL is intent (as we've seen) on partnering with sports betting companies then they should provide the fans with salary and contract data. Maybe not specifically who has which teams on limited NMC/NTC, or even centralized attendance figures... but at the very least it should offer what CapFriendly used to.