The straight answer to "Are roulette machines in casinos fixed?" is found at the wheel. Roulette looks like pure chance, and it is, but the rules still decide how much any bet costs. A European wheel has one green zero, an American wheel adds a second, and French tables add rules that return half of some losing bets. Knowing which wheel is in play, what each bet pays and what the zero takes is most of what there is to know about playing roulette sensibly.
Speed matters as much as the edge. A busy live table manages around forty spins an hour, while an automated wheel or an online game can run several times as many, and each spin charges the same percentage of whatever is staked. Whether roulette is worth playing depends on treating that cost as the price of entertainment: at a slow table a fixed budget lasts an evening, at a fast screen the same budget can be gone in minutes.
Licensed roulette wheels are not rigged: they are tested and balanced, and casinos log results so that a biased wheel would show up in the numbers. Balls are not weighted; they are made to a standard size and material, and a worn wheel is replaced rather than exploited. Roulette machines use a random number generator that is checked in the same way and cannot be fixed by the casino. Under licensing regulations there are no illegal bets on the layout itself, although devices that try to predict the ball are banned almost everywhere.
Call bets are placed by name on French layouts; the neighbours bet covers a chosen number plus the two pockets either side of it on the wheel.
On a single zero wheel the chance is one in thirty seven, and on a double zero wheel one in thirty eight for each green pocket.
Licensed wheels are tested and balanced, results are logged so bias would show, balls are made to a standard, and electronic machines use checked random number generators.
Each spin charges the same share of the stake, so a live table at about forty spins an hour drains a budget far slower than a fast online game.
Systems only alter the size and rhythm of stakes; every spin is independent and every bet keeps the same edge, so no pattern predicts the next number.
When zero lands, la partage gives back half of any even money stake, so each of those outside chances costs the player half what it would on an ordinary single zero table.