In their day, some of the illegal Casinos would have compared favorably to Las Vegas Casinos in the 50's. Some had big name entertainment of the era, long before LV ever thought of it.
Re: Arrowhead 1933, Beverly Hills 1937. Several in AC, 1930's. Pacific Club, Honolulu 1853. Yes 18 is correct.
In 1933 LV casinos still had sawdust floors.
NV learned that big name entertainment drew customers and they learned it from the illegals.
Yes, the illegals certainly deserve the word "Casino."