It might seem to be a funny question and it is not my Kavono to appear so but Tosfos says in his Maskonoh that there are many places in Shas that the Gemoro can say "ULETAAMEYCH" and it chooses not to so that is why here it does not.
Please could you be kind enough to give me Lekol Hapochus 2 examples of what Tosfos means where the Gemoro chooses not to follow such a line of reasoning
Shkoyach Boruch Kahan
Boruch Kahan, London England
1) Tosfos in Kesuvos 12b, DH Rav Huna, writes that the Gemara there could have said "ul'Ta'ameich." Tosfos writes that we say Bari is better than Shema only when the Bari is good and the Shema is bad. Tosfos asks on this rule from the Sugya in Kesuvos where Abaye says that we say that even a bad Bari is better than a good Shema. Tosfos writes that the Gemara itself could have argued to Abaye, "ul'Ta'ameich."
2) We also find this in Tosfos in Bava Metzia 42a, DH Amar Shmuel. Tosfos there discusses the Gemara in Bava Kama 57a. The practical question of Tosfos is, what is the Din if the Shomer buried the money 100 Amos underground and it was stolen from there? Tosfos attempts to prove from Bava Kama 57a that the only possible Ones, when it comes to theft, is if armed robbers stole it. This suggests that any other scenario is not considered an Ones, and this would include even when it was stolen after being buried 100 Amos deep into the ground. Tosfos refutes this and writes that the Gemara could have said "ul'Ta'ameich" -- not only are armed robbers an Ones, but being stolen from 100 Amos down is also an Ones.
Kol Tuv,
Dovid Bloom