If you've already got them to drive to the place and walk up to the ticket booth with money in hand, it is unlikely they are going to turn around and leave before paying the price to enter. This is not to say it is okay to mistreat these customers but rather to point out that unscrupulous online casinos seldom have a blanket policy of cheating every player the same. Oops!, did I say cheating? I meant treating every player the same. The smart ones are very careful about choosing their battles and they almost always involve large sums of money and a player who has little or no backing and a guaranteed sad story which may or may not be true. Since that player joined the casino through a search engine and not a portal, there is nobody with a financial concern the player gets treated right past the generic outlook of third-party gambling websites who are actively on the watch for casinos not treating players fairly (to remove them from their list) and they wouldn't notice said injustice because these situations usually require investigation that can take days worth of time. If the player didn't sign up through a third-party gambling website then there isn't anybody with a deep enough investment in the matter to warrant spending the time to find out. It remains the player's word against the casino. The player loses in the eyes of the majority at least until more come forward and make the same claim.
There just isn't enough time to run around investigating every unfounded accusation so gambling portal owners wait for a trend or pattern to show and then they investigate to see if they want to continue listing the casino (or network) in question but that seldom helps the people who got ripped-off in the beginning. Which as mentioned are going to be those who arrived without any recourse, because it will happen to them before it happens to players arriving from websites that can stop sending any further players at any given time.
While it is true that in the case of casinos it is paramount they provide excellent customer support and treatment at all times or they will not see that customer again, it is also true that if they lose that customer, all they lose is the one person. In the case of unscrupulous online casinos that don't like to pay out on big money withdrawals, they have no qualms what-so-ever about losing the one customer in order to save not paying out money they know they'd never likely see again, ... this an equation these kind of places use to evaluate based on that player's past proven wagering history at that casino, and if it comes back the casino would never make its money back any time soon, then these places choose to just not pay the withdrawal. However that all changes if that player had joined the casino through a third-party website that chooses which gaming establishments are listed there and which ones are left out.
Even with that customer going around speaking ill of the casino at every possible turn, there is no way that one person could ever influence enough peers to be more than a drop in a bucket compared to how many customers a gambling portal represents on a consistent basis. Therefore if you want to be treated better than the average person, you have already made a big step in the right direction by choosing your online casino from a third-party gambling website and not just by finding it on a search engine.