Sforno on Genesis 34:10/ספורנו על בראשית ל״ד:י׳

1וסחרוה,. Event though normally, newcomers were not allowed to engage in the kind of commerce or artisanship which would compete with that practiced by the local inhabitants. We have this principle in Baba Batra 21, where it is spelled out as the right of the local inhabitant who feels economically threatened by competition from a new immigrant. He is accorded the right to lodge a complaint against the newcomer practicing his trade in his town. [an ancient form of the policy of “closed shop.” Ed.]