libdvdcss is also consider to be illegal for distribution in the US as it is circumvention tool in violation of DMCA
It is a legal gray area if a individual who obtains libdvdcss breaks the law by using it, however no software vendor can include it if they are a US Company
This is why VLC, Handbrake, and many other organizations that distribute it are very very clear they are not US Organizations and exist outside the Jurisdiction of US Courts
Even in the vhs days, ntsc v pal, and the lack of international awareness that was common pre internet, provided region locking of a sort.