You sure about that? I've read that the backgrounds have a lower resolution in the PC version, just like the FMV did in the original 1998 port.
I am 100% positive.
The backgrounds in the PC version *did* have a lower resolution relative to the rest of the game, even back in 1998, because the game ran on PC at double the horizontal and vertical resolution vs the PS1 version (640x480 instead of 320x240). This applied to models and a few redrawn textures (fonts, mostly), but backgrounds were still the same low-res backgrounds as the PS1 version, which looked worse in this context. It looks sillier still today with our 1080p and all that.
But the final 240p output on PS1 is the single best evidence of my point. It wouldn't have made any sense to have higher-res backgrounds, since the additional detail would've been lost when output over such a low resolution anyway.