[Landlord] Short Term Advice

I've been renting one of my units fully furnished on furniture finder. Usually 2-4 month stays, I'm frequently asked by people on this platform why there is a lease. Airbnb doesn't have a lease. Hotels don't have leases. I'd appreciate advice that gives me any insight that holds these in juxtaposition to my situation. Personally I won't roll without my lease but would like to make a better argument than—because I say so.

Is there a 30 day mark for example where their stay automatically becomes covered under certain laws. BTW—This is in Illinois and not in Chicago.