As you know, these two interiors have absolutely no tangible objects. That is, in fact, only the floor has a collision. Even the walls are missing. That allows you to see through them. But this fix adds a collision with the correct materials to absolutely every object. Even the back room, where the Big Bear goes, also has a collision. But you can get there only with the help of a noclip.
Installation:
Replace the file "gen_int3_1.col" in the archive "gta_int.img", using any img editor. Well, or use Modloader. Also, if for some reason you have a modification that replaces these collisions, then in the "Manual installation" folder there are files "bdups_interior"; "bdups_plant" and so on. They need to be replaced with identical collisions in "gen_int3_1.col" via the Colleditor.
When distributing a modification on third-party sites -indicate the author.