Silly question but makes me curious.
* Why was she given so much regard when she came in
there are several possibilities
1. he is the son of a casino owner
2. maybe she is a great female gambler in your town but you don't know her yet (i think you should date her)
3. Maybe women gamblers rarely go to casinos, so everyone is a bit amazed to see them
4. Why don't you ask in person when you are at the casino? it will be clearer.
* How are female gamblers treated in your neighborhood?
in my country gambling is prohibited. so no women gamble in my area
for sure, your #1 possibility is not the case. as she is a woman, so he is not the son.

but more then likely, because the woman is said to be very pretty and fair looking lady. and since physical casino is mostly flocked by men, they usually don't expect such lady to enter and bet. and since she's the only woman as per the situation presented, these men let the woman do her business first before them. not a big deal for them if she's the last one who entered.
that's what I mean.
it's very rare for beautiful women to enter gambling and gamble there (maybe). because according to the OP's story several male gamblers who were there looked shocked when they saw the woman enter through the front door of the lobby.
but I'm sure she must be so beautiful that all male gamblers marvel.
what I was thinking was that if all the men there were amazed by the female gambler when they entered for the first time, what if they suddenly challenged all the men there to gamble. whether the men there will fight her or just silently see her beauty