The tone of the ads is a bit off-putting, but it reflects the attitude of the day. It's amazing how little the basic design has changed over the years and how most women still don't use them or even know about them. I genuinely impressed by GYN/OB when I told her I used one!

I like the middle one that says, "For mature women only." Like if you're going to make jokes about it, you can't have one! I guess I better send mine back!
I take the mature woman thing to mean more along the lines of a non-virginal type of thing. Like for a young, virginal girl it might be more difficult to use? Idk...
Probably more along the lines of they don't want virgins to use it because people might get in an uproar-- "She'll rupture her maidenhead!" "It'll lead to masturbation!"-- that sort of thing. Ye Olden Dayes stupidity.
I'm pretty sure that's what it means, too, and I think "mature" woman was code for non-virgin. Sort of like R-rated movies are "for mature audiences only."
Yep, I think it means "post-virginal" as well, since you have to have your fingers all up in your business to use it. Sometimes the euphemisms are so bizarre that it takes me years to figure them out. When I was a young teen, the FAQ booklet with Tampax included, "Can single girls use Tampax?" Since my mom bought them for me, I was puzzled by the question for years. I finally realized it meant, "Will Tampax rupture my hymen?"