In this context "managed on commercial lines" means managed by a business, company, or corporation - instead of a family. For example, McDonalds owns farms that would be managed commercially. But, families can also own farms that would be called independent (they are not owned by a company)

Zander, along/ on the lines (plural) of = similar to; in a similar way; with the traits or characteristics of Vienna and Berlin are modernist cities, almost along the lines of Chicago. ---------------- strictly on commercial lines = as a business in order to make profits -It is necessary that market research service should be provided strictly on commercial lines. -As in almost every other case agriculture will succeed if it develops along commercial lines rather than some ideological blueprint. -------------- business run on/along family lines = to provide employment and profits for family members and/or friends -The first farms, given what we know from anthropology, were likely organized along family lines. -Central American drug cartels work mostly along family lines.