There is a difference there. Factory owners who dump are actively breaking the law themselves. The motel owner isn't doing any drug dealing, just renting rooms.

I don't think this is any different to ISPs having to police what their users are doing. For a motel owner to know about drug dealing they need to see it happening, but that's not possible behind closed doors, unless they use surveillance, which is illegal and unethical.

Similarly, ISPs who facilitate users who use their Internet access to download child porn have no way of knowing about this, unless they implement surveillance. This is unethical and illegal... Yet the crime is arguably worse!