The chance of the ball arriving in a particular slot was unaffected. But if a player introduces a method that lets them know where the ball will end up in advance, and lets only them know this and not the other players, it is cheating as defined by NRS 465.015.
This does at least alter the value of a wagering instrument.
It also alters the elements of chance. Not of the chances regarding which number comes up, but of the chances of the players to pick the right number. It is up to the casino to make roulette a game of pure chance - but for all players alike.
By your argument using poker as an example1), it would be okay not to just “read” the other players by looking for tells in their body language, but actually read their cards (or the cards in the deck) with “electronic assistance” or by using marked cards. This is basically using information that is in the public domain versus using inside information.
1) Which is arguably apples and quinces. Roulette is, as you say, a game of pure chance. There is no system. Unless the wheel is tampered with, results are random.2)
Poker is a combination of chance (the luck of the draw) and skill.
2) I had the opportunity to take a behind the scenes tour of a newly opened casino in the late 1980ies. They kept track of all the numbers on all the tables and used computers and statistical methods to make sure the numbers really were random. If any hint of a pattern would start to emerge, 1) that particular table went into unscheduled maintenance right away 2) extra checks on the floor for any signs of collusion between personnel and patrons were made.
What really surprised me was that during all opening hours of the casino there were at least three civil servants from the IRS on the premises to keep an eye on things.
