Why not have research to allow the installation of pollution scrubbers? Higher tier pollution scrubbers means less pollution is vented to the outside.

Not gonna happen. My reasoning:

If a fixed percentage of pollution were filtered upon exit, you could just use Recursion 2 to pack everything several extra layers deep to abuse the mechanic in a way that is neither fun nor UPS efficient.

If a constant amount of pollution were filtered, it would be not much different from any other pollution scrubber mod. Install a pollution scrubber mod instead.