Happy mode does exist, I was part of a team that sold A.I. to William Hill a couple years back. William Hill also have installed face recognition in their FOBTs to stop the same people getting jackpots.
Brand new fresh accounts with virgin players who have not shown up in the system before are put on happy mode.
And yes, you are correct about deleting your account but it not making a difference as you are already in “the machine”. There are ways of getting around this, but it is beyond the technical skill of most. But if anyone is interested I am more than happy to divulge the various methods you can use to look like a brand new fresh player.