Delegating the work does not delegate the liability, and fair housing law says so in terms. HUD's regulation at 24 CFR 100.7(b) provides that "a person is vicariously liable for a discriminatory housing practice by the person's agent or employee, regardless of whether the person knew or should have known of the conduct that resulted in a discriminatory housing practice, consistent with agency law." There is no knowledge requirement and no diligence defense. If a manager screens applicants in a way that violates the Fair Housing Act, the owner is liable for it.
The same rule adds a second, separate route. Under 24 CFR 100.7(a)(1)(ii) a person is directly liable for "failing to take prompt action to correct and end a discriminatory housing practice by that person's employee or agent, where the person knew or should have known of the discriminatory conduct," and paragraph (a)(1)(iii) extends the same duty to a third party's conduct where the person knew or should have known and "had the power to correct it." So an owner who learns of a problem and leaves it to the manager has acquired a liability of their own on top of the vicarious one. The regulation also closes the obvious wrong response: prompt action "may not include any action that penalizes or harms the aggrieved person, such as eviction of the aggrieved person."
The manager holds money that is not theirs, and that is regulated separately from the management itself. Rent belongs to the owner and security deposits belong, conditionally, to the tenants, yet both flow through the manager's accounts. States handle this through trust-account rules aimed at whoever holds funds for another. California's is representative in structure: Business and Professions Code section 10145(a)(1) requires a real estate broker who accepts "funds belonging to others" to place them immediately into a neutral escrow depository, into the principal's hands, or into a trust fund account, where they must remain "until disbursed by the broker in accordance with instructions from the person entitled to the funds." An owner evaluating a manager should know which account the rent lands in and how the deposits are held, because those are the two balances the owner and the tenants are exposed to.
Whether a license is required is a state question, and the answer is frequently yes for reasons that surprise owners. The activity that triggers licensing is usually not "management" as such but collecting rent or leasing on behalf of someone else for compensation. California again illustrates the pattern: Business and Professions Code section 10131(b) makes a person a real estate broker if, for compensation and for another, they lease or rent property, solicit for prospective tenants, or collect "rents from real property, or improvements thereon." Not every state routes the activity through a broker's license. Oregon licenses a "licensed real estate property manager" as its own class alongside its broker classes, under ORS chapter 696. Two states can therefore reach the same activity through entirely different licenses, which is why this is a question to ask of the specific state rather than to assume from a general rule.
What the fee actually is cannot be looked up, and that absence is the honest answer. No regulator, no federal agency and no standards body publishes a market range for property management fees, and every circulating figure traces to a management company's own marketing or to an aggregation of it. So the useful comparison is not a percentage but the whole schedule: what the ongoing fee covers; whether a separate leasing or placement fee is charged when a tenant is found; whether there is a renewal fee; how maintenance is billed and whether the manager marks up invoices or takes a coordination fee; who keeps late fees, application fees and pet fees; what the fee is when a unit sits vacant; and what notice ends the agreement. Two managers quoting the same monthly rate can cost very different amounts once those lines are added.