I am afraid I still do not quite see the point about speculating over photographs as to what someone may or may not be wearing underneath.
This forum has ben around long enough for most people associated with it to know that some women chose to wear a bra and some do not. Of those that do not, some choose to conceal the fact, others make it obvious, and some don't care. How you dress is a matter of choice.
Nobody has to wear a bra, and nobody should stare rudely at a woman who does not, although if you choose not to and your breasts are obvious, you can expect some looks just as might with a low neckline or a very short skirt or dress.
It really is not a big deal!