True. However, keep in mind all is relative.
If you are a well put-together man who flies first class, the flight attendants there are lower tier easy-to-meet girls for you... compared to what you could get.
Flight attendants are often good-looking. But rarely stunners. They're also less educated and intelligent than the women successful men have access to. Men in the manosphere like to say intelligence and education don't matter for women... however, studies consistently find, at least with marriage, both sexes marry their intellectual, educational, and economic peers. Were you to meet a wealthy man with a beautiful, intelligent, educated wife he met at random somewhere, and then a wealthy man with a beautiful flight attendant wife he met on a long-haul flight, you'd likely view those as quite different. Or at least I would. I realize some guys view flight attendants as status boosters to date (for some reason. They're not hard to meet at all if you frequent bars popular with flight crew).
Beautiful women are more likely to attend malls, functions, etc., where more successful foreign men (or more successful local men) are in higher attendance, this is very true! This is a way to raise their availability as well. It's on the spectrum, somewhere between "Go somewhere I will just bump into men left and right" vs. "Stay in and never go out except to buy groceries and work." A woman's choice of profession may have an element of this... women who pursue professional careers often do so in small or large part because they want access to professional men. You can look at all sorts of activities women pursue and ask yourself "How far out of her way has she gone to make herself available to the men she'd like to meet?"
The general rule applies across all scenarios: the more out-of-her-way she's gone to make herself more available, the more likely she is to be an 'easy-to-meet girl'.