Most dealers are ignorant
I would think someone in that enviroment 8 or more hours a day would know better, especially if they are trained to "spot" counters ????
Dealers are not trained to spot counters. They are trained only on the mechanics of dealing the game.
For example, the Mohave Community College in Bullhead City, AZ has a dealer training course that provides virtually all the new dealers for the Laughlin casinos. The class is six weeks in length, and the class workbook is about 75 pages. There is nothing in the book or in the class presentation about simple basic strategy, let alone any forms of advantage play, other than outright cheating, such as capping bets.
The Mohave Community College program is considered one of the best, so I imagine that the quickie, for-profit grind-them-out type schools in Las Vegas are even less thorough. Some students have not even played casino games in their lives, so have no preconceived ideas. If they have played, it was as a ploppy, with all the same superstitious voodoo nonsense that most ploppies believe in.
Casino personnel are taught things on a "need to know" basis. The dealer needs to know how to keep the game moving, how to yell "Checks play" at times set by casino policy, and how to yell "Floor" if there is any problem. Anything else is unnecessary.
Though some will pick up things on their own, if interested and motivated, most are merely there to put in their eight hours, and get a paycheck. To most, it is merely a dull, boring, repetitive factory job. The ones to watch out for are the ones who want to move up into supervision or casino management. They are the ones motivated enough to learn extra things, usually on their own. Once they have that casino mindset, they mirror the casino management's view of wanting every patron to lose every penny they have. If they know correct advice, they certainly won't tell a player. And they cartainly won't be above outright lying to a player. Lying to customers is simply a part of casino employment.
Remember that for most, it's "just a job" -- they don't care to know more.