Marco had become Ruth Wilcox's personal driver now, where he didn't have to do anything else and wasn't managed by anyone, so his status at the hotel was special, and he had money now, so his attire was quite dashing.
Of course, this might also be related to Ruth Wilcox, because as a fierce tiger, she wouldn't allow a sloppy, snotty person to be her driver.
As her driver, you had to pay attention to your appearance from top to bottom; otherwise, you'd be in for a lecture. Fleur Carson and Yusuf Zuck knew this all too well.
Marco could relate to this too, which is why he was still wearing a suit despite the scorching heat.
It wasn't strange, then, that the cashier sister proactively asked him out to dinner, because clearly, the newly-arrived Brother Marco had a special relationship with Ms. Wilcox, and was on brotherly terms with Director Zuck.
Calling the chairman brother and messing around—could he possibly be a regular employee? So, the cashier sister did have some insight.