The issue with FA's is not their age, gender, ethnicity, or body type, it's unions and how well the airline treats them. Obviously someone new (again, no matter their age, gender, ethnicity, or body type) is going to be more cautious/nicer to passengers because they aren't so "in" with the union. Someone who's been working and in the union for years isn't going to care about how well they treat other passengers, co-workers, or their job because short of murder, the union is going to defend and allow them to keep their job.

Now there are some exceptions, such as how well the airline treats them and if they like their job. For example, Southwest is heavily unionized yet most of their flight attendants go above and beyond. Likewise, over at United, they have many flight attendants that only do the bare minimum, if even, because of how they feel the company treats them.