Escorts and Age

I know, at least it is not new for more experienced hobbyists, but some escorts do not become older.
Meanwhile I have found one having different ages, depending where she posts her ad. Then she is 28, 29 and one time 31 years of age.
The age of 30 seems to be a barrier which escorts do not want to exceed.
But why are some escorts having this problem? I personally prefer a cultivated lady of 40 years of age to a 25 years old slut