In addition to the answer given by @msh210 there's an important nuance as well.
The concept of "Arvus" means that I'm a guarantor for you, individually. The Jewish people undertook the responsibility to watch out for each other.
The second source isn't focused on the people doing the sin. It's not the same mitzvah a "tochacha", rebuke. That is a mitzvah to rebuke and correct my fellow Jew- as the verse states Vayikra 19:17:
לֹֽא־תִשְׂנָ֥א אֶת־אָחִ֖יךָ בִּלְבָבֶ֑ךָ הוֹכֵ֤חַ תּוֹכִ֙יחַ֙
אֶת־עֲמִיתֶ֔ךָ וְלֹא־תִשָּׂ֥א עָלָ֖יו חֵֽטְא׃
You shall not hate your kinsfolk in your heart. Reprove your kinsman
but incur no guilt because of him.
Tochacha is based upon my concern for the person, and my desire/obligation to distance him from sinning.
The obligation is only to rebuke someone who is still halachically considered my kinsman, and there a numerous regulations about how much I am obligated to rebuke him.
(See Gemara Erachin 16b and thererabout)
Tochacha fits very well with the concept of arvus.
Here, it's a different mitzvah- macha'ah, protest. There's a mitzvah to protest evil being done in the world.
This obligation is not out of concern for the individual, but for the resulting chillul Hashem cause by sin. Thus even for those people for whom I have no need to rebuke ("the whole world" who are clearly not my kinsmen), I still need to protest- to avoid being part of his chillul Hashem.
This point is discussed a lot in conjunction to chillul shabbos here in Israel. By making a public rally against cars driving in religious neighborhoods, it might fulfill the mitzvah of machaah-protest but it will not fulfill the concept of tochacha-rebuke.
By reaching out to individual drivers, in a nice way, it might be a fulfillment of tochaha but generally you'll need to avoid making a public statement of protest. There's lots discussion regarding how to determine which approach to take.
I've heard lots of oral discussion on this point. They all quote Ritva, which I looked up in his commentary once (I think on maseches beitza, in the sugya of "mutav yehiyu shoggegim", but I can't check it now) who discusses this issue.
The point is that the two concepts are very different conceptually, and come from different sources, even though there may practically be some overlap.