We recorded plenty of movies off TV in the 90s and had 2 VCRs. But the few times we tried making a copy of a rental VHS tape resulted in an unusable copy due to MacroVision. Point being I don’t think copying rental tapes by the end customer was a huge problem for the movie studios, unless I just got unlucky and MacroVision wasn’t as pervasive as I thought.
Someone else mentioned independent video stores copying tapes to rent and that I find more likely to have been a concern.