Not quite correct. Not in European casinos, at any rate.
When zero comes up the “even money bets” (red:black; odd:even; high:low) are not immediately lost. Depending on the house, one of two rules comes into play. Some casinos operate “Le Partage” and half the stake is lost. Others operate the “En Prison” rule. In this case the stake remains on the table “in prison” until the next spin. If it wins, the stake is returned (without any winnings) and if it loses it is forfeited.
Both these systems have the same effect on the game’s odds. The House has an “edge” (i.e. makes its margin of profit) by only paying 35-1 for the single number bets when in fact the true odds are 36-1. Similar differences are apparent for betting on pairs, rows or blocks of numbers. This is about 2.78% (on a wheel with just zero – some wheels, particularly in the USA have zero and double zero). They would also make a similar percentage (2.70%) on the even money bets as, on average, one in 37 spins will result in those bets being lost. The “Le Partage” and “En Prison” rules cut that percentage in half.
Most casinos in the USA do not operate these rules and even money bets on zero (or double zero where used) are immediately lost.