A normal European roulette wheel only has a 0, and it does NOT include a 00. So a European, or single-zero, roulette wheel only has 37 numbers total, 0-36. An American wheel, on the other hand, has 0-36, but it also has a 00, which gives a total of 38 numbers on the wheel. This doesn't mean you won't ever see a roulette game in Europe with a 00, and it also doesn't mean that no casinos in America have single zero roulette; those are just the standards in the two areas.
In fact, the Monte Carlo Casino in Las Vegas, which has a European theme, definitely has a single zero roulette game. And in competitive casino markets like Mississippi, it's not hard to find a single zero roulette game either. You just have to be on the lookout for one.
The odds of any given number coming up on a single zero roulette wheel are 36 to 1. On a standard American roulette wheel, the odds are 37 to 1. In either case, roulette pays out 35 to 1 for the bet, so it's pretty easy to see how the casino makes its profit at a roulette table. This makes the house edge on American roulette 5.26%, which means for every $100 bet, a player will lose an average of $5.26 over time. Since the odds are better on European roulette, the house edge is only about 2.7%, which means you'll only lose $2.70 per $100 bet.
Compared to blackjack, which has a house edge of 0.5% when played with perfect strategy (2% when you don't know basic strategy), roulette doesn't seem like a very good bet, even the single zero version. In fact, craps has a house edge of 1.4%, so it seems like a better bet too. (Although some of the craps bets that are available are just dreadful in terms of odds.) But in terms of hourly cost, a single zero roulette can become downright competitive with these other games, because a player will almost always be making fewer bets per hour.
A blackjack game can offer 50 bets per hour at a full table, and if there are fewer people at the table, you might make 200 bets per hour. Often a craps table will have 100 rolls per hour. But roulette, with its slower and more elegant pace, tops out at about 65 bets per hour, and at a full table, usually averages closer to just 30 spins per hour.
Let's say an average blackjack player bets $5 per hand and plays 50 hands per hour, or $250 of action per hour, and loses 2%. That's an average $5 per hour cost to play blackjack. Compare that with 30 roulette spins in an hour at $5 each. That's $150 in action with a 2.7% edge, for a total cost of $4.05. Order a couple of premium beers and you've made a profit at the roulette table.
Some single zero roulette games also offer an optional rule called en prison, which allows a player who loses an even money bet to consider his bet "in prison" instead of lost. If your next spin comes in as what you bet originally, you get your bet back, but no winnings. If you lose again, then you lose the bet. This cuts the house edge on a European roulette game with the en prison rule in effect to a respectable 1.35%, which is a pretty low house edge.