I think beginner accounts that have a high win rate are intentionally given to them to attract beginner accounts to come back the next day. But that doesn't seem to be the case for most of them because only the truly lucky ones will win the big bucks. But we also don't know what casinos do to attract newbies and we only know casinos do promotions to get more newbies playing on their sites.
Obviously, any good business must carefully calculate its income and expenses in order to maximize profits. And any casino, of course, also makes such calculations. And there is no problem for programmers to make a link to the game options for new players and those who have registered an account for a long time. Of course, it is logical that new players are given the opportunity to win a little more. And thus encourage them to continue playing. And it certainly does.
And at the same time, it is quite legally possible to justify this simply by promoting and advertising this casino.