Ain holchin b'mamon achar haRov (II)

The gemara in B.M. attempts to prove that in a location where a large number of people pass, any lost object is considered abandoned by its owner even if it has simanim. The gemara cites a mishna in machshirim which states that if a majority of the residents of a city are nochrim, one who finds a lost object is not chayav to announce it to determine the owner - we assume that it has been abandoned because of the presence of the majority, proving at least with respect to a majority of nochrim passing through the din holds. Tosfos asks why we need the sevara that the presence of a majority of nochrim in the city causes ye'ush, causes the owner to abandon hope of getting the object back - we should simply argue that if the majority of the city residents are nochrim then the likelihood is that a nochri dropped the object and there is no mitzvah of hashavas aveidah? The achronim point out that this Tosfos seems to contradict the rule we have discussed before that "ain holchin b'mamon achar harov", we cannot resolve financial questions using the principle of rov. One may need to draw a distinction between where title (chezkas marei kammah) exists and one is trying to use rov to prove that someone else is the real owner (which rov cannot do) and the case of aveidah where we do not know who originally had title to the object and that is what we are trying to use rov to determine.