Modesty, touching, etc.

What if Shmuel's statement, "a market in a woman's pubic area," meant that there was a line (although there is disagreement about what a market is)?

According to the Ritva, this is interpreted as a statement about Samuel's time and place, and not something that cannot change.

Regarding C-D, do you have sources (or lack thereof) for this?
Does this stem from your interpretation of the sources that prohibit touching as referring to touching that leads to relationships?

Modesty is related to a much broader division between a decent woman and an immodest woman. A decent woman dresses modestly to prevent her body from becoming a commodity for sale. An immodest woman – including maidservants and slaves – is a woman whose body is for sale. She can be bought, her sexuality can be used against her will (her master hands her over to his slave or, according to the Maimonides, a Torah law can come upon her) and she has no autonomy in relation to it. Halacha has never needed to discuss these distinctions because the assumption was that these matters belong to the way of the land. Jewish women are decent women who dress in accordance with the way decent women dress (and are not displayed naked in the market as merchandise for sale). What has happened in our time is that decent women have begun to dress as immodest women. This is related to sexual permissiveness and the commercialization of sexuality. And suddenly Halacha has been required to express a clear position on how a decent woman dresses.
And even in Tel Aviv itself, on the beach in the mornings, when secular women come to the beach with their small children, they wear a robe to prevent the commercialization of their sexuality.

There are reviews about it online.
For example: https://yhb.org.il/shiurim/%D7%A0%D7%92%D7%99%D7%A2%D7%94-%D7%91%D7%A2%D7%A8%D7%99%D7%95%D7%AA-%D7%9E%D7%AA%D7%99-%D7%90%D7%A1%D7%95%D7%A8%D7%94-%D7%95%D7%9E%D7%AA%D7%99-%D7%9E%D7%95%D7%AA%D7%A8%D7%AA/

And also here: https://www.yeshiva.org.il/ask/104296 He refers to Rabbi Haber's book, “You are modest, wise”. You can read there.

In Blessings 24: Indeed, the Ritva writes about touching a woman's private parts that it is about places that are usually covered, and this indeed seems to depend on time and place, but regarding the ruling on "shaving a woman's private parts," he writes that it is even if one is accustomed to revealing it, and not according to the words of the Rabbi? (And this is also explained in such a way that since touching a woman's private parts, why did Shmuel add "shaving a woman's private parts"? Isn't this even two hundred mena? But "shaving a woman's private parts" is not dependent on time and place, etc.)

The Ritva I was talking about is at the end of Kiddushin:

Everything is according to the will of God. And so the way of life is according to what a person knows for himself, if it is appropriate for him to distance himself from his desire, he does it, and even looking at a woman's colorful clothes is forbidden, as is stated in Tractate Avoda Zara (22:2), and if he knows for himself that his desire has surrendered and is subject to it and does not harbor any grudge, he is permitted to look at and speak with the nakedness and ask about the peace of a man's wife, and that is what Rabbi Yochanan (22:44) said of Ash'ari, who bathed and did not hesitate to think about the evil desire, and Rabbi Ami Denfaki said of her, "Amma'ta Debi Caesar" (Ketubot 17:1), and several of the rabbis of the Demishta tribe, who are also Matronyta (above 4:1), and Rav Ada bar Ahavah, who said in Ketubot (ibid.), "He covered her shoulders and danced in her and did not hesitate to contemplate her." From the reason they said this, but it is not appropriate to be lenient in this except for a great Hasid who recognizes his inclination, and not all scholars trust their inclinations as much as they do their hearing in all that they worship their images, and blessed is he who overcomes his inclinations and his labor and training in the Torah, for the words of the Torah stand for a person in his childhood and give him an afterlife and hope for his old age, as it is said that they will be renewed again in their return, fertile and fresh.

Perhaps he is only dealing with the uniqueness and closeness to the naked and not with looking at the market.
But the essence of the problem is not necessarily more difficult than Samuel. It is possible that in his time this would have seemed problematic regardless of the place and circumstances, and still in another period this could change. Thus, the Garden discussed the matter of a woman's head covering, and as is known in some places and times there were women who feared not to cover their heads.
And beyond that, Samuel is talking about praying in front of the pubic area and not necessarily about the laws of modesty.