Most startups and companies (try to) act in good faith and will acquire a license. And, if they did not, they should foresee the legal and operational consequences.
Well YouTube was similar when it first started, no? People were uploading whatever they wanted, and eventually they rolled out DMCA takedown and reporting features for copyright infringement violations.
Over time, the service was setup with a full feature set to handle all of this, but it didn't exist when YouTube first started.
