Avira, you are contradicting yourself. Initially you said that even before R’ Yochanan met the אלמנה he knew that of course a man should do this; the אלמנה taught him that even a woman should do this. Now you’re saying, “we don’t learn anything specific about (sic) women from this story.”
The concept that a person should be מטריח themselves to get more שכר is גופא the concept of שכר פסיעות: the אלמנה was teaching him that the more you are טורח the more שכר you get.
Rav and R’ Yochanan did not discuss personally every מחלוקת that they had: Rav lived in בבל and R’ Yochanan lived in Eretz Yisroel. They weren’t aware of all each other’s teachings, כדמוכח from בבא קמא קיז (the story with R’ Yochanan and Rav Kahana.) Indeed, R’ Abba, who was R’ Yochanan’s תלמיד, had to ask the תלמידים of Rav how Rav explained the פסוקים, because he didn’t know himself. That discussion is the source of the מחלוקת, as is obvious from the גמרא.
After the גמרא records the two פשטים of Rav and Rebbi Yochanan, the גמרא says רבי יוחנן לטעמיה דאמר שכר פסיעות יש. This makes it very clear that the מחלוקת is based on Rebbi Yochanan holding that there is a concept of שכר פסיעות, and Rav holding that there isn’t.