Why does Rashi cite Gen. 13:10 as an example at Num. 15:15, if it isn't really an example?

Question

Sh'lach, 15:1–16, speaks of the flour, oil, and wine that accompanied certain animal offerings. Verse 15 says, in part:

חֻקַּת עוֹלָם לְדֹרֹתֵיכֶם כָּכֶם כַּגֵּר יִהְיֶה לִפְנֵי ה׳

Pretty literally:

An eternal law for your generations; like you like the stranger shall be before God.

Rashi explains that last part:

ככם כגר ― כמותכם כן גר וכן דרך לשון עברית כגן ה׳ כארץ מצרים כן ארץ מצרים כמוני כמוך כעמי כעמך

like you like the stranger ― [means] "like you, so is the stranger". That's the way of Hebrew, [as in] "כגן ה׳ כארץ מצרים", [literally "like the garden of God like the land of Egypt", means "like the garden of God,] so is the land of Egypt[". Likewise,] "כמוני כמוך כעמי כעמך", [literally "like me, like you, like my nation, like your nation", means "like me, so are you; like my nation, so is your nation".]

The first quotation in Rashi, "כגן ה׳ כארץ מצרים", is from Lech L'cha 13:10. (The second is from Ⅰ Melachim 22:4, by the way.) The problem is that Rashi's explanation here in Sh'lach doesn't really fit the verse there in Lech L'cha, and, especially, doesn't fit with his own explanation there. The verse there says:

וַיִּשָּׂא לוֹט אֶת עֵינָיו וַיַּרְא אֶת כָּל כִּכַּר הַיַּרְדֵּן כִּי כֻלָּהּ מַשְׁקֶה לִפְנֵי שַׁחֵת ה׳ אֶת סְדֹם וְאֶת עֲמֹרָה כְּגַן ה׳ כְּאֶרֶץ מִצְרַיִם בֹּאֲכָה צֹעַר

Lot looked up and saw the whole Jordan plain, that it was all moist, before God's destroying Sodom and Gomorrah, like God's garden like the land of Egypt, as you come to Zoar.

Here, interpreting "כְּגַן ה׳ כְּאֶרֶץ מִצְרַיִם" as "like God's garden, so is Egypt" doesn't seem to make sense, since we're trying to describe not Egypt but the Jordan plain. And, indeed, Rashi interprets both "כְּגַן ה׳" and "כְּאֶרֶץ מִצְרַיִם" as comparisons to the Jordan plain, not to one another. He writes:

כגן ה׳ ― לאילנות
כארץ מצרים ― לזרעים

like God's garden ― for trees
like the land of Egypt ― for seeds

Why does Rashi cite that verse in Lech L'cha as an example of the linguistic phenomenon he's describing in Sh'lach? It isn't one, according to him.

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I've looked in Mizrachi, L'vush, and Gur Arye to no avail, so turn to you.

Answer 1

The citation from Lech Lecha is referring to the idea that the valley around Sodom and Gomorrah, which is called HaShem's Garden, was irrigated from the river like the man made irrigation system used in Egypt. This is in contrast to relying upon rain.

Rashi isn't making a comparison from these two citations, but only giving examples of the grammar usage of the double 'Kaf' prefix.