Rachi seems to say that for RABA, the reason we need to say this Routz laharetz is because in case someone finds a get in the garbage with the same names. Why don't we apply the same logic in Israel(where he can also find a get in the garbage with the same names)of saying befanai nichtav befanai nichatam for RABA?
yonatane, csl,canada
Rashi merely says that they do not necessarily know that they must write a Get Lishmah. Being that in Eretz Yisrael they do know that a Get must be written Lishmah, there is no suspicion that anyone will use a Get that was not written for this woman and this man. [If you have a question on a specific Rashi, please cite the Rashi you are referring to by using its Dibur Hamaschil.]
All the best,
Yaakov Montrose